881 lines
27 KiB
C
881 lines
27 KiB
C
/* Floating point routines for GDB, the GNU debugger.
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Copyright (C) 1986-2017 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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/* Support for converting target fp numbers into host DOUBLEST format. */
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/* XXX - This code should really be in libiberty/floatformat.c,
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however configuration issues with libiberty made this very
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difficult to do in the available time. */
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#include "defs.h"
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#include "doublest.h"
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#include "floatformat.h"
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#include "gdbtypes.h"
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#include <math.h> /* ldexp */
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#include <algorithm>
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/* The odds that CHAR_BIT will be anything but 8 are low enough that I'm not
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going to bother with trying to muck around with whether it is defined in
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a system header, what we do if not, etc. */
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#define FLOATFORMAT_CHAR_BIT 8
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/* The number of bytes that the largest floating-point type that we
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can convert to doublest will need. */
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#define FLOATFORMAT_LARGEST_BYTES 16
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/* Extract a field which starts at START and is LEN bytes long. DATA and
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TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */
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static unsigned long
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get_field (const bfd_byte *data, enum floatformat_byteorders order,
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unsigned int total_len, unsigned int start, unsigned int len)
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{
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unsigned long result;
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unsigned int cur_byte;
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int cur_bitshift;
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/* Caller must byte-swap words before calling this routine. */
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gdb_assert (order == floatformat_little || order == floatformat_big);
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/* Start at the least significant part of the field. */
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if (order == floatformat_little)
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{
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/* We start counting from the other end (i.e, from the high bytes
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rather than the low bytes). As such, we need to be concerned
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with what happens if bit 0 doesn't start on a byte boundary.
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I.e, we need to properly handle the case where total_len is
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not evenly divisible by 8. So we compute ``excess'' which
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represents the number of bits from the end of our starting
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byte needed to get to bit 0. */
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int excess = FLOATFORMAT_CHAR_BIT - (total_len % FLOATFORMAT_CHAR_BIT);
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cur_byte = (total_len / FLOATFORMAT_CHAR_BIT)
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- ((start + len + excess) / FLOATFORMAT_CHAR_BIT);
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cur_bitshift = ((start + len + excess) % FLOATFORMAT_CHAR_BIT)
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- FLOATFORMAT_CHAR_BIT;
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}
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else
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{
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cur_byte = (start + len) / FLOATFORMAT_CHAR_BIT;
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cur_bitshift =
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((start + len) % FLOATFORMAT_CHAR_BIT) - FLOATFORMAT_CHAR_BIT;
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}
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if (cur_bitshift > -FLOATFORMAT_CHAR_BIT)
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result = *(data + cur_byte) >> (-cur_bitshift);
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else
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result = 0;
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cur_bitshift += FLOATFORMAT_CHAR_BIT;
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if (order == floatformat_little)
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++cur_byte;
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else
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--cur_byte;
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/* Move towards the most significant part of the field. */
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while (cur_bitshift < len)
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{
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result |= (unsigned long)*(data + cur_byte) << cur_bitshift;
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cur_bitshift += FLOATFORMAT_CHAR_BIT;
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switch (order)
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{
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case floatformat_little:
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++cur_byte;
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break;
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case floatformat_big:
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--cur_byte;
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break;
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}
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}
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if (len < sizeof(result) * FLOATFORMAT_CHAR_BIT)
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/* Mask out bits which are not part of the field. */
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result &= ((1UL << len) - 1);
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return result;
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}
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/* Normalize the byte order of FROM into TO. If no normalization is
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needed then FMT->byteorder is returned and TO is not changed;
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otherwise the format of the normalized form in TO is returned. */
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static enum floatformat_byteorders
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floatformat_normalize_byteorder (const struct floatformat *fmt,
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const void *from, void *to)
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{
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const unsigned char *swapin;
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unsigned char *swapout;
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int words;
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if (fmt->byteorder == floatformat_little
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|| fmt->byteorder == floatformat_big)
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return fmt->byteorder;
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words = fmt->totalsize / FLOATFORMAT_CHAR_BIT;
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words >>= 2;
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swapout = (unsigned char *)to;
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swapin = (const unsigned char *)from;
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if (fmt->byteorder == floatformat_vax)
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{
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while (words-- > 0)
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{
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*swapout++ = swapin[1];
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*swapout++ = swapin[0];
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*swapout++ = swapin[3];
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*swapout++ = swapin[2];
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swapin += 4;
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}
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/* This may look weird, since VAX is little-endian, but it is
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easier to translate to big-endian than to little-endian. */
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return floatformat_big;
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}
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else
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{
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gdb_assert (fmt->byteorder == floatformat_littlebyte_bigword);
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while (words-- > 0)
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{
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*swapout++ = swapin[3];
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*swapout++ = swapin[2];
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*swapout++ = swapin[1];
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*swapout++ = swapin[0];
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swapin += 4;
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}
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return floatformat_big;
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}
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}
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/* Convert from FMT to a DOUBLEST.
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FROM is the address of the extended float.
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Store the DOUBLEST in *TO. */
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static void
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convert_floatformat_to_doublest (const struct floatformat *fmt,
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const void *from,
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DOUBLEST *to)
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{
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unsigned char *ufrom = (unsigned char *) from;
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DOUBLEST dto;
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long exponent;
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unsigned long mant;
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unsigned int mant_bits, mant_off;
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int mant_bits_left;
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int special_exponent; /* It's a NaN, denorm or zero. */
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enum floatformat_byteorders order;
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unsigned char newfrom[FLOATFORMAT_LARGEST_BYTES];
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enum float_kind kind;
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gdb_assert (fmt->totalsize
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<= FLOATFORMAT_LARGEST_BYTES * FLOATFORMAT_CHAR_BIT);
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/* For non-numbers, reuse libiberty's logic to find the correct
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format. We do not lose any precision in this case by passing
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through a double. */
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kind = floatformat_classify (fmt, (const bfd_byte *) from);
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if (kind == float_infinite || kind == float_nan)
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{
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double dto;
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floatformat_to_double (fmt->split_half ? fmt->split_half : fmt,
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from, &dto);
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*to = (DOUBLEST) dto;
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return;
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}
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order = floatformat_normalize_byteorder (fmt, ufrom, newfrom);
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if (order != fmt->byteorder)
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ufrom = newfrom;
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if (fmt->split_half)
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{
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DOUBLEST dtop, dbot;
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floatformat_to_doublest (fmt->split_half, ufrom, &dtop);
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/* Preserve the sign of 0, which is the sign of the top
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half. */
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if (dtop == 0.0)
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{
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*to = dtop;
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return;
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}
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floatformat_to_doublest (fmt->split_half,
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ufrom + fmt->totalsize / FLOATFORMAT_CHAR_BIT / 2,
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&dbot);
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*to = dtop + dbot;
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return;
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}
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exponent = get_field (ufrom, order, fmt->totalsize, fmt->exp_start,
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fmt->exp_len);
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/* Note that if exponent indicates a NaN, we can't really do anything useful
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(not knowing if the host has NaN's, or how to build one). So it will
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end up as an infinity or something close; that is OK. */
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mant_bits_left = fmt->man_len;
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mant_off = fmt->man_start;
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dto = 0.0;
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special_exponent = exponent == 0 || exponent == fmt->exp_nan;
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/* Don't bias NaNs. Use minimum exponent for denorms. For
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simplicity, we don't check for zero as the exponent doesn't matter.
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Note the cast to int; exp_bias is unsigned, so it's important to
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make sure the operation is done in signed arithmetic. */
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if (!special_exponent)
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exponent -= fmt->exp_bias;
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else if (exponent == 0)
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exponent = 1 - fmt->exp_bias;
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/* Build the result algebraically. Might go infinite, underflow, etc;
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who cares. */
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/* If this format uses a hidden bit, explicitly add it in now. Otherwise,
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increment the exponent by one to account for the integer bit. */
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if (!special_exponent)
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{
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if (fmt->intbit == floatformat_intbit_no)
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dto = ldexp (1.0, exponent);
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else
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exponent++;
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}
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while (mant_bits_left > 0)
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{
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mant_bits = std::min (mant_bits_left, 32);
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mant = get_field (ufrom, order, fmt->totalsize, mant_off, mant_bits);
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dto += ldexp ((double) mant, exponent - mant_bits);
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exponent -= mant_bits;
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mant_off += mant_bits;
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mant_bits_left -= mant_bits;
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}
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/* Negate it if negative. */
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if (get_field (ufrom, order, fmt->totalsize, fmt->sign_start, 1))
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dto = -dto;
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*to = dto;
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}
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/* Set a field which starts at START and is LEN bytes long. DATA and
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TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */
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static void
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put_field (unsigned char *data, enum floatformat_byteorders order,
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unsigned int total_len, unsigned int start, unsigned int len,
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unsigned long stuff_to_put)
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{
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unsigned int cur_byte;
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int cur_bitshift;
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/* Caller must byte-swap words before calling this routine. */
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gdb_assert (order == floatformat_little || order == floatformat_big);
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/* Start at the least significant part of the field. */
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if (order == floatformat_little)
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{
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int excess = FLOATFORMAT_CHAR_BIT - (total_len % FLOATFORMAT_CHAR_BIT);
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cur_byte = (total_len / FLOATFORMAT_CHAR_BIT)
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- ((start + len + excess) / FLOATFORMAT_CHAR_BIT);
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cur_bitshift = ((start + len + excess) % FLOATFORMAT_CHAR_BIT)
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- FLOATFORMAT_CHAR_BIT;
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}
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else
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{
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cur_byte = (start + len) / FLOATFORMAT_CHAR_BIT;
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cur_bitshift =
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((start + len) % FLOATFORMAT_CHAR_BIT) - FLOATFORMAT_CHAR_BIT;
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}
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if (cur_bitshift > -FLOATFORMAT_CHAR_BIT)
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{
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*(data + cur_byte) &=
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~(((1 << ((start + len) % FLOATFORMAT_CHAR_BIT)) - 1)
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<< (-cur_bitshift));
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*(data + cur_byte) |=
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(stuff_to_put & ((1 << FLOATFORMAT_CHAR_BIT) - 1)) << (-cur_bitshift);
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}
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cur_bitshift += FLOATFORMAT_CHAR_BIT;
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if (order == floatformat_little)
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++cur_byte;
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else
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--cur_byte;
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/* Move towards the most significant part of the field. */
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while (cur_bitshift < len)
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{
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if (len - cur_bitshift < FLOATFORMAT_CHAR_BIT)
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{
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/* This is the last byte. */
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*(data + cur_byte) &=
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~((1 << (len - cur_bitshift)) - 1);
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*(data + cur_byte) |= (stuff_to_put >> cur_bitshift);
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}
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else
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*(data + cur_byte) = ((stuff_to_put >> cur_bitshift)
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& ((1 << FLOATFORMAT_CHAR_BIT) - 1));
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cur_bitshift += FLOATFORMAT_CHAR_BIT;
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if (order == floatformat_little)
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++cur_byte;
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else
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--cur_byte;
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}
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}
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/* The converse: convert the DOUBLEST *FROM to an extended float and
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store where TO points. Neither FROM nor TO have any alignment
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restrictions. */
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static void
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convert_doublest_to_floatformat (const struct floatformat *fmt,
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const DOUBLEST *from, void *to)
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{
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DOUBLEST dfrom;
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int exponent;
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DOUBLEST mant;
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unsigned int mant_bits, mant_off;
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int mant_bits_left;
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unsigned char *uto = (unsigned char *) to;
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enum floatformat_byteorders order = fmt->byteorder;
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unsigned char newto[FLOATFORMAT_LARGEST_BYTES];
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if (order != floatformat_little)
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order = floatformat_big;
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if (order != fmt->byteorder)
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uto = newto;
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memcpy (&dfrom, from, sizeof (dfrom));
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memset (uto, 0, (fmt->totalsize + FLOATFORMAT_CHAR_BIT - 1)
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/ FLOATFORMAT_CHAR_BIT);
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if (fmt->split_half)
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{
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/* Use static volatile to ensure that any excess precision is
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removed via storing in memory, and so the top half really is
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the result of converting to double. */
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static volatile double dtop, dbot;
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DOUBLEST dtopnv, dbotnv;
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dtop = (double) dfrom;
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/* If the rounded top half is Inf, the bottom must be 0 not NaN
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or Inf. */
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if (dtop + dtop == dtop && dtop != 0.0)
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dbot = 0.0;
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else
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dbot = (double) (dfrom - (DOUBLEST) dtop);
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dtopnv = dtop;
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dbotnv = dbot;
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floatformat_from_doublest (fmt->split_half, &dtopnv, uto);
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floatformat_from_doublest (fmt->split_half, &dbotnv,
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(uto
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+ fmt->totalsize / FLOATFORMAT_CHAR_BIT / 2));
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return;
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}
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if (dfrom == 0)
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return; /* Result is zero */
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if (dfrom != dfrom) /* Result is NaN */
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{
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/* From is NaN */
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put_field (uto, order, fmt->totalsize, fmt->exp_start,
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fmt->exp_len, fmt->exp_nan);
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/* Be sure it's not infinity, but NaN value is irrel. */
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put_field (uto, order, fmt->totalsize, fmt->man_start,
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fmt->man_len, 1);
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goto finalize_byteorder;
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}
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/* If negative, set the sign bit. */
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if (dfrom < 0)
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{
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put_field (uto, order, fmt->totalsize, fmt->sign_start, 1, 1);
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dfrom = -dfrom;
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}
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if (dfrom + dfrom == dfrom && dfrom != 0.0) /* Result is Infinity. */
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{
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/* Infinity exponent is same as NaN's. */
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put_field (uto, order, fmt->totalsize, fmt->exp_start,
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fmt->exp_len, fmt->exp_nan);
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/* Infinity mantissa is all zeroes. */
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put_field (uto, order, fmt->totalsize, fmt->man_start,
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fmt->man_len, 0);
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goto finalize_byteorder;
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}
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#ifdef HAVE_LONG_DOUBLE
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mant = frexpl (dfrom, &exponent);
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#else
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mant = frexp (dfrom, &exponent);
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#endif
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if (exponent + fmt->exp_bias <= 0)
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{
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/* The value is too small to be expressed in the destination
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type (not enough bits in the exponent. Treat as 0. */
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put_field (uto, order, fmt->totalsize, fmt->exp_start,
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fmt->exp_len, 0);
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put_field (uto, order, fmt->totalsize, fmt->man_start,
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fmt->man_len, 0);
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goto finalize_byteorder;
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}
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if (exponent + fmt->exp_bias >= (1 << fmt->exp_len))
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{
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/* The value is too large to fit into the destination.
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Treat as infinity. */
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put_field (uto, order, fmt->totalsize, fmt->exp_start,
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fmt->exp_len, fmt->exp_nan);
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put_field (uto, order, fmt->totalsize, fmt->man_start,
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fmt->man_len, 0);
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goto finalize_byteorder;
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}
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put_field (uto, order, fmt->totalsize, fmt->exp_start, fmt->exp_len,
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exponent + fmt->exp_bias - 1);
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mant_bits_left = fmt->man_len;
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mant_off = fmt->man_start;
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while (mant_bits_left > 0)
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{
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unsigned long mant_long;
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mant_bits = mant_bits_left < 32 ? mant_bits_left : 32;
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mant *= 4294967296.0;
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mant_long = ((unsigned long) mant) & 0xffffffffL;
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mant -= mant_long;
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/* If the integer bit is implicit, then we need to discard it.
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If we are discarding a zero, we should be (but are not) creating
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a denormalized number which means adjusting the exponent
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(I think). */
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if (mant_bits_left == fmt->man_len
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&& fmt->intbit == floatformat_intbit_no)
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{
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mant_long <<= 1;
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mant_long &= 0xffffffffL;
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/* If we are processing the top 32 mantissa bits of a doublest
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so as to convert to a float value with implied integer bit,
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we will only be putting 31 of those 32 bits into the
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final value due to the discarding of the top bit. In the
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case of a small float value where the number of mantissa
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bits is less than 32, discarding the top bit does not alter
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the number of bits we will be adding to the result. */
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if (mant_bits == 32)
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mant_bits -= 1;
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}
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if (mant_bits < 32)
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{
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/* The bits we want are in the most significant MANT_BITS bits of
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mant_long. Move them to the least significant. */
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mant_long >>= 32 - mant_bits;
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}
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put_field (uto, order, fmt->totalsize,
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mant_off, mant_bits, mant_long);
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mant_off += mant_bits;
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mant_bits_left -= mant_bits;
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}
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finalize_byteorder:
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/* Do we need to byte-swap the words in the result? */
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if (order != fmt->byteorder)
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floatformat_normalize_byteorder (fmt, newto, to);
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}
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||
/* Check if VAL (which is assumed to be a floating point number whose
|
||
format is described by FMT) is negative. */
|
||
|
||
int
|
||
floatformat_is_negative (const struct floatformat *fmt,
|
||
const bfd_byte *uval)
|
||
{
|
||
enum floatformat_byteorders order;
|
||
unsigned char newfrom[FLOATFORMAT_LARGEST_BYTES];
|
||
|
||
gdb_assert (fmt != NULL);
|
||
gdb_assert (fmt->totalsize
|
||
<= FLOATFORMAT_LARGEST_BYTES * FLOATFORMAT_CHAR_BIT);
|
||
|
||
/* An IBM long double (a two element array of double) always takes the
|
||
sign of the first double. */
|
||
if (fmt->split_half)
|
||
fmt = fmt->split_half;
|
||
|
||
order = floatformat_normalize_byteorder (fmt, uval, newfrom);
|
||
|
||
if (order != fmt->byteorder)
|
||
uval = newfrom;
|
||
|
||
return get_field (uval, order, fmt->totalsize, fmt->sign_start, 1);
|
||
}
|
||
|
||
/* Check if VAL is "not a number" (NaN) for FMT. */
|
||
|
||
enum float_kind
|
||
floatformat_classify (const struct floatformat *fmt,
|
||
const bfd_byte *uval)
|
||
{
|
||
long exponent;
|
||
unsigned long mant;
|
||
unsigned int mant_bits, mant_off;
|
||
int mant_bits_left;
|
||
enum floatformat_byteorders order;
|
||
unsigned char newfrom[FLOATFORMAT_LARGEST_BYTES];
|
||
int mant_zero;
|
||
|
||
gdb_assert (fmt != NULL);
|
||
gdb_assert (fmt->totalsize
|
||
<= FLOATFORMAT_LARGEST_BYTES * FLOATFORMAT_CHAR_BIT);
|
||
|
||
/* An IBM long double (a two element array of double) can be classified
|
||
by looking at the first double. inf and nan are specified as
|
||
ignoring the second double. zero and subnormal will always have
|
||
the second double 0.0 if the long double is correctly rounded. */
|
||
if (fmt->split_half)
|
||
fmt = fmt->split_half;
|
||
|
||
order = floatformat_normalize_byteorder (fmt, uval, newfrom);
|
||
|
||
if (order != fmt->byteorder)
|
||
uval = newfrom;
|
||
|
||
exponent = get_field (uval, order, fmt->totalsize, fmt->exp_start,
|
||
fmt->exp_len);
|
||
|
||
mant_bits_left = fmt->man_len;
|
||
mant_off = fmt->man_start;
|
||
|
||
mant_zero = 1;
|
||
while (mant_bits_left > 0)
|
||
{
|
||
mant_bits = std::min (mant_bits_left, 32);
|
||
|
||
mant = get_field (uval, order, fmt->totalsize, mant_off, mant_bits);
|
||
|
||
/* If there is an explicit integer bit, mask it off. */
|
||
if (mant_off == fmt->man_start
|
||
&& fmt->intbit == floatformat_intbit_yes)
|
||
mant &= ~(1 << (mant_bits - 1));
|
||
|
||
if (mant)
|
||
{
|
||
mant_zero = 0;
|
||
break;
|
||
}
|
||
|
||
mant_off += mant_bits;
|
||
mant_bits_left -= mant_bits;
|
||
}
|
||
|
||
/* If exp_nan is not set, assume that inf, NaN, and subnormals are not
|
||
supported. */
|
||
if (! fmt->exp_nan)
|
||
{
|
||
if (mant_zero)
|
||
return float_zero;
|
||
else
|
||
return float_normal;
|
||
}
|
||
|
||
if (exponent == 0 && !mant_zero)
|
||
return float_subnormal;
|
||
|
||
if (exponent == fmt->exp_nan)
|
||
{
|
||
if (mant_zero)
|
||
return float_infinite;
|
||
else
|
||
return float_nan;
|
||
}
|
||
|
||
if (mant_zero)
|
||
return float_zero;
|
||
|
||
return float_normal;
|
||
}
|
||
|
||
/* Convert the mantissa of VAL (which is assumed to be a floating
|
||
point number whose format is described by FMT) into a hexadecimal
|
||
and store it in a static string. Return a pointer to that string. */
|
||
|
||
const char *
|
||
floatformat_mantissa (const struct floatformat *fmt,
|
||
const bfd_byte *val)
|
||
{
|
||
unsigned char *uval = (unsigned char *) val;
|
||
unsigned long mant;
|
||
unsigned int mant_bits, mant_off;
|
||
int mant_bits_left;
|
||
static char res[50];
|
||
char buf[9];
|
||
int len;
|
||
enum floatformat_byteorders order;
|
||
unsigned char newfrom[FLOATFORMAT_LARGEST_BYTES];
|
||
|
||
gdb_assert (fmt != NULL);
|
||
gdb_assert (fmt->totalsize
|
||
<= FLOATFORMAT_LARGEST_BYTES * FLOATFORMAT_CHAR_BIT);
|
||
|
||
/* For IBM long double (a two element array of double), return the
|
||
mantissa of the first double. The problem with returning the
|
||
actual mantissa from both doubles is that there can be an
|
||
arbitrary number of implied 0's or 1's between the mantissas
|
||
of the first and second double. In any case, this function
|
||
is only used for dumping out nans, and a nan is specified to
|
||
ignore the value in the second double. */
|
||
if (fmt->split_half)
|
||
fmt = fmt->split_half;
|
||
|
||
order = floatformat_normalize_byteorder (fmt, uval, newfrom);
|
||
|
||
if (order != fmt->byteorder)
|
||
uval = newfrom;
|
||
|
||
if (! fmt->exp_nan)
|
||
return 0;
|
||
|
||
/* Make sure we have enough room to store the mantissa. */
|
||
gdb_assert (sizeof res > ((fmt->man_len + 7) / 8) * 2);
|
||
|
||
mant_off = fmt->man_start;
|
||
mant_bits_left = fmt->man_len;
|
||
mant_bits = (mant_bits_left % 32) > 0 ? mant_bits_left % 32 : 32;
|
||
|
||
mant = get_field (uval, order, fmt->totalsize, mant_off, mant_bits);
|
||
|
||
len = xsnprintf (res, sizeof res, "%lx", mant);
|
||
|
||
mant_off += mant_bits;
|
||
mant_bits_left -= mant_bits;
|
||
|
||
while (mant_bits_left > 0)
|
||
{
|
||
mant = get_field (uval, order, fmt->totalsize, mant_off, 32);
|
||
|
||
xsnprintf (buf, sizeof buf, "%08lx", mant);
|
||
gdb_assert (len + strlen (buf) <= sizeof res);
|
||
strcat (res, buf);
|
||
|
||
mant_off += 32;
|
||
mant_bits_left -= 32;
|
||
}
|
||
|
||
return res;
|
||
}
|
||
|
||
|
||
/* Convert TO/FROM target to the hosts DOUBLEST floating-point format.
|
||
|
||
If the host and target formats agree, we just copy the raw data
|
||
into the appropriate type of variable and return, letting the host
|
||
increase precision as necessary. Otherwise, we call the conversion
|
||
routine and let it do the dirty work. Note that even if the target
|
||
and host floating-point formats match, the length of the types
|
||
might still be different, so the conversion routines must make sure
|
||
to not overrun any buffers. For example, on x86, long double is
|
||
the 80-bit extended precision type on both 32-bit and 64-bit ABIs,
|
||
but by default it is stored as 12 bytes on 32-bit, and 16 bytes on
|
||
64-bit, for alignment reasons. See comment in store_typed_floating
|
||
for a discussion about zeroing out remaining bytes in the target
|
||
buffer. */
|
||
|
||
static const struct floatformat *host_float_format = GDB_HOST_FLOAT_FORMAT;
|
||
static const struct floatformat *host_double_format = GDB_HOST_DOUBLE_FORMAT;
|
||
static const struct floatformat *host_long_double_format
|
||
= GDB_HOST_LONG_DOUBLE_FORMAT;
|
||
|
||
/* See doublest.h. */
|
||
|
||
size_t
|
||
floatformat_totalsize_bytes (const struct floatformat *fmt)
|
||
{
|
||
return ((fmt->totalsize + FLOATFORMAT_CHAR_BIT - 1)
|
||
/ FLOATFORMAT_CHAR_BIT);
|
||
}
|
||
|
||
void
|
||
floatformat_to_doublest (const struct floatformat *fmt,
|
||
const void *in, DOUBLEST *out)
|
||
{
|
||
gdb_assert (fmt != NULL);
|
||
|
||
if (fmt == host_float_format)
|
||
{
|
||
float val = 0;
|
||
|
||
memcpy (&val, in, floatformat_totalsize_bytes (fmt));
|
||
*out = val;
|
||
}
|
||
else if (fmt == host_double_format)
|
||
{
|
||
double val = 0;
|
||
|
||
memcpy (&val, in, floatformat_totalsize_bytes (fmt));
|
||
*out = val;
|
||
}
|
||
else if (fmt == host_long_double_format)
|
||
{
|
||
long double val = 0;
|
||
|
||
memcpy (&val, in, floatformat_totalsize_bytes (fmt));
|
||
*out = val;
|
||
}
|
||
else
|
||
convert_floatformat_to_doublest (fmt, in, out);
|
||
}
|
||
|
||
void
|
||
floatformat_from_doublest (const struct floatformat *fmt,
|
||
const DOUBLEST *in, void *out)
|
||
{
|
||
gdb_assert (fmt != NULL);
|
||
|
||
if (fmt == host_float_format)
|
||
{
|
||
float val = *in;
|
||
|
||
memcpy (out, &val, floatformat_totalsize_bytes (fmt));
|
||
}
|
||
else if (fmt == host_double_format)
|
||
{
|
||
double val = *in;
|
||
|
||
memcpy (out, &val, floatformat_totalsize_bytes (fmt));
|
||
}
|
||
else if (fmt == host_long_double_format)
|
||
{
|
||
long double val = *in;
|
||
|
||
memcpy (out, &val, floatformat_totalsize_bytes (fmt));
|
||
}
|
||
else
|
||
convert_doublest_to_floatformat (fmt, in, out);
|
||
}
|
||
|
||
|
||
/* Return the floating-point format for a floating-point variable of
|
||
type TYPE. */
|
||
|
||
const struct floatformat *
|
||
floatformat_from_type (const struct type *type)
|
||
{
|
||
struct gdbarch *gdbarch = get_type_arch (type);
|
||
const struct floatformat *fmt;
|
||
|
||
gdb_assert (TYPE_CODE (type) == TYPE_CODE_FLT);
|
||
gdb_assert (TYPE_FLOATFORMAT (type));
|
||
fmt = TYPE_FLOATFORMAT (type)[gdbarch_byte_order (gdbarch)];
|
||
gdb_assert (TYPE_LENGTH (type) >= floatformat_totalsize_bytes (fmt));
|
||
return fmt;
|
||
}
|
||
|
||
/* Extract a floating-point number of type TYPE from a target-order
|
||
byte-stream at ADDR. Returns the value as type DOUBLEST. */
|
||
|
||
DOUBLEST
|
||
extract_typed_floating (const void *addr, const struct type *type)
|
||
{
|
||
const struct floatformat *fmt = floatformat_from_type (type);
|
||
DOUBLEST retval;
|
||
|
||
floatformat_to_doublest (fmt, addr, &retval);
|
||
return retval;
|
||
}
|
||
|
||
/* Store VAL as a floating-point number of type TYPE to a target-order
|
||
byte-stream at ADDR. */
|
||
|
||
void
|
||
store_typed_floating (void *addr, const struct type *type, DOUBLEST val)
|
||
{
|
||
const struct floatformat *fmt = floatformat_from_type (type);
|
||
|
||
/* FIXME: kettenis/2001-10-28: It is debatable whether we should
|
||
zero out any remaining bytes in the target buffer when TYPE is
|
||
longer than the actual underlying floating-point format. Perhaps
|
||
we should store a fixed bitpattern in those remaining bytes,
|
||
instead of zero, or perhaps we shouldn't touch those remaining
|
||
bytes at all.
|
||
|
||
NOTE: cagney/2001-10-28: With the way things currently work, it
|
||
isn't a good idea to leave the end bits undefined. This is
|
||
because GDB writes out the entire sizeof(<floating>) bits of the
|
||
floating-point type even though the value might only be stored
|
||
in, and the target processor may only refer to, the first N <
|
||
TYPE_LENGTH (type) bits. If the end of the buffer wasn't
|
||
initialized, GDB would write undefined data to the target. An
|
||
errant program, refering to that undefined data, would then
|
||
become non-deterministic.
|
||
|
||
See also the function convert_typed_floating below. */
|
||
memset (addr, 0, TYPE_LENGTH (type));
|
||
|
||
floatformat_from_doublest (fmt, &val, addr);
|
||
}
|
||
|
||
/* Convert a floating-point number of type FROM_TYPE from a
|
||
target-order byte-stream at FROM to a floating-point number of type
|
||
TO_TYPE, and store it to a target-order byte-stream at TO. */
|
||
|
||
void
|
||
convert_typed_floating (const void *from, const struct type *from_type,
|
||
void *to, const struct type *to_type)
|
||
{
|
||
const struct floatformat *from_fmt = floatformat_from_type (from_type);
|
||
const struct floatformat *to_fmt = floatformat_from_type (to_type);
|
||
|
||
if (from_fmt == NULL || to_fmt == NULL)
|
||
{
|
||
/* If we don't know the floating-point format of FROM_TYPE or
|
||
TO_TYPE, there's not much we can do. We might make the
|
||
assumption that if the length of FROM_TYPE and TO_TYPE match,
|
||
their floating-point format would match too, but that
|
||
assumption might be wrong on targets that support
|
||
floating-point types that only differ in endianness for
|
||
example. So we warn instead, and zero out the target buffer. */
|
||
warning (_("Can't convert floating-point number to desired type."));
|
||
memset (to, 0, TYPE_LENGTH (to_type));
|
||
}
|
||
else if (from_fmt == to_fmt)
|
||
{
|
||
/* We're in business. The floating-point format of FROM_TYPE
|
||
and TO_TYPE match. However, even though the floating-point
|
||
format matches, the length of the type might still be
|
||
different. Make sure we don't overrun any buffers. See
|
||
comment in store_typed_floating for a discussion about
|
||
zeroing out remaining bytes in the target buffer. */
|
||
memset (to, 0, TYPE_LENGTH (to_type));
|
||
memcpy (to, from, std::min (TYPE_LENGTH (from_type),
|
||
TYPE_LENGTH (to_type)));
|
||
}
|
||
else
|
||
{
|
||
/* The floating-point types don't match. The best we can do
|
||
(apart from simulating the target FPU) is converting to the
|
||
widest floating-point type supported by the host, and then
|
||
again to the desired type. */
|
||
DOUBLEST d;
|
||
|
||
floatformat_to_doublest (from_fmt, from, &d);
|
||
floatformat_from_doublest (to_fmt, &d, to);
|
||
}
|
||
}
|