314 lines
7.6 KiB
C
314 lines
7.6 KiB
C
/* Signed and unsigned multiplication and division and modulus for CRIS.
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Contributed by Axis Communications.
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Written by Hans-Peter Nilsson <hp@axis.se>, c:a 1992.
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Copyright (C) 1998-2018 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the
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Free Software Foundation; either version 3, or (at your option) any
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later version.
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This file is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>. */
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/* Note that we provide prototypes for all "const" functions, to attach
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the const attribute. This is necessary in 2.7.2 - adding the
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attribute to the function *definition* is a syntax error.
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This did not work with e.g. 2.1; back then, the return type had to
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be "const". */
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#include "config.h"
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#if defined (__CRIS_arch_version) && __CRIS_arch_version >= 3
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#define LZ(v) __builtin_clz (v)
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#endif
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/* In (at least) the 4.7 series, GCC doesn't automatically choose the
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most optimal strategy, possibly related to insufficient modelling of
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delay-slot costs. */
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#if defined (__CRIS_arch_version) && __CRIS_arch_version >= 10
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#define SIGNMULT(s, a) ((s) * (a)) /* Cheap multiplication, better than branch. */
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#else
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#define SIGNMULT(s, a) ((s) < 0 ? -(a) : (a)) /* Branches are still better. */
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#endif
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#if defined (L_udivsi3) || defined (L_divsi3) || defined (L_umodsi3) \
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|| defined (L_modsi3)
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/* Result type of divmod worker function. */
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struct quot_rem
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{
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long quot;
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long rem;
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};
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/* This is the worker function for div and mod. It is inlined into the
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respective library function. Parameter A must have bit 31 == 0. */
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static __inline__ struct quot_rem
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do_31div (unsigned long a, unsigned long b)
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__attribute__ ((__const__, __always_inline__));
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static __inline__ struct quot_rem
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do_31div (unsigned long a, unsigned long b)
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{
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/* Adjust operands and result if a is 31 bits. */
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long extra = 0;
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int quot_digits = 0;
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if (b == 0)
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{
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struct quot_rem ret;
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ret.quot = 0xffffffff;
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ret.rem = 0xffffffff;
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return ret;
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}
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if (a < b)
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return (struct quot_rem) { 0, a };
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#ifdef LZ
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if (b <= a)
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{
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quot_digits = LZ (b) - LZ (a);
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quot_digits += (a >= (b << quot_digits));
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b <<= quot_digits;
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}
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#else
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while (b <= a)
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{
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b <<= 1;
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quot_digits++;
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}
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#endif
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/* Is a 31 bits? Note that bit 31 is handled by the caller. */
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if (a & 0x40000000)
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{
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/* Then make b:s highest bit max 0x40000000, because it must have
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been 0x80000000 to be 1 bit higher than a. */
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b >>= 1;
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/* Adjust a to be maximum 0x3fffffff, i.e. two upper bits zero. */
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if (a >= b)
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{
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a -= b;
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extra = 1 << (quot_digits - 1);
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}
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else
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{
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a -= b >> 1;
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/* Remember that we adjusted a by subtracting b * 2 ** Something. */
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extra = 1 << quot_digits;
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}
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/* The number of quotient digits will be one less, because
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we just adjusted b. */
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quot_digits--;
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}
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/* Now do the division part. */
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/* Subtract b and add ones to the right when a >= b
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i.e. "a - (b - 1) == (a - b) + 1". */
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b--;
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#define DS __asm__ ("dstep %2,%0" : "=r" (a) : "0" (a), "r" (b))
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switch (quot_digits)
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{
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case 32: DS; case 31: DS; case 30: DS; case 29: DS;
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case 28: DS; case 27: DS; case 26: DS; case 25: DS;
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case 24: DS; case 23: DS; case 22: DS; case 21: DS;
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case 20: DS; case 19: DS; case 18: DS; case 17: DS;
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case 16: DS; case 15: DS; case 14: DS; case 13: DS;
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case 12: DS; case 11: DS; case 10: DS; case 9: DS;
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case 8: DS; case 7: DS; case 6: DS; case 5: DS;
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case 4: DS; case 3: DS; case 2: DS; case 1: DS;
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case 0:;
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}
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{
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struct quot_rem ret;
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ret.quot = (a & ((1 << quot_digits) - 1)) + extra;
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ret.rem = a >> quot_digits;
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return ret;
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}
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}
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#ifdef L_udivsi3
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unsigned long
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__Udiv (unsigned long a, unsigned long b) __attribute__ ((__const__));
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unsigned long
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__Udiv (unsigned long a, unsigned long b)
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{
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long extra = 0;
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/* Adjust operands and result, if a and/or b is 32 bits. */
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/* Effectively: b & 0x80000000. */
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if ((long) b < 0)
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return a >= b;
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/* Effectively: a & 0x80000000. */
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if ((long) a < 0)
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{
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int tmp = 0;
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if (b == 0)
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return 0xffffffff;
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#ifdef LZ
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tmp = LZ (b);
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#else
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for (tmp = 31; (((long) b & (1 << tmp)) == 0); tmp--)
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;
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tmp = 31 - tmp;
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#endif
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if ((b << tmp) > a)
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{
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extra = 1 << (tmp-1);
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a -= b << (tmp - 1);
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}
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else
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{
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extra = 1 << tmp;
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a -= b << tmp;
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}
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}
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return do_31div (a, b).quot+extra;
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}
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#endif /* L_udivsi3 */
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#ifdef L_divsi3
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long
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__Div (long a, long b) __attribute__ ((__const__));
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long
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__Div (long a, long b)
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{
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long extra = 0;
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long sign = (b < 0) ? -1 : 1;
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long res;
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/* We need to handle a == -2147483648 as expected and must while
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doing that avoid producing a sequence like "abs (a) < 0" as GCC
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may optimize out the test. That sequence may not be obvious as
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we call inline functions. Testing for a being negative and
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handling (presumably much rarer than positive) enables us to get
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a bit of optimization for an (accumulated) reduction of the
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penalty of the 0x80000000 special-case. */
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if (a < 0)
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{
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sign = -sign;
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if ((a & 0x7fffffff) == 0)
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{
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/* We're at 0x80000000. Tread carefully. */
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a -= SIGNMULT (sign, b);
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extra = sign;
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}
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a = -a;
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}
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res = do_31div (a, __builtin_labs (b)).quot;
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return SIGNMULT (sign, res) + extra;
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}
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#endif /* L_divsi3 */
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#ifdef L_umodsi3
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unsigned long
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__Umod (unsigned long a, unsigned long b) __attribute__ ((__const__));
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unsigned long
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__Umod (unsigned long a, unsigned long b)
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{
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/* Adjust operands and result if a and/or b is 32 bits. */
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if ((long) b < 0)
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return a >= b ? a - b : a;
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if ((long) a < 0)
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{
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int tmp = 0;
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if (b == 0)
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return a;
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#ifdef LZ
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tmp = LZ (b);
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#else
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for (tmp = 31; (((long) b & (1 << tmp)) == 0); tmp--)
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;
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tmp = 31 - tmp;
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#endif
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if ((b << tmp) > a)
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{
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a -= b << (tmp - 1);
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}
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else
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{
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a -= b << tmp;
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}
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}
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return do_31div (a, b).rem;
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}
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#endif /* L_umodsi3 */
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#ifdef L_modsi3
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long
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__Mod (long a, long b) __attribute__ ((__const__));
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long
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__Mod (long a, long b)
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{
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long sign = 1;
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long res;
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/* We need to handle a == -2147483648 as expected and must while
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doing that avoid producing a sequence like "abs (a) < 0" as GCC
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may optimize out the test. That sequence may not be obvious as
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we call inline functions. Testing for a being negative and
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handling (presumably much rarer than positive) enables us to get
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a bit of optimization for an (accumulated) reduction of the
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penalty of the 0x80000000 special-case. */
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if (a < 0)
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{
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sign = -1;
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if ((a & 0x7fffffff) == 0)
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/* We're at 0x80000000. Tread carefully. */
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a += __builtin_labs (b);
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a = -a;
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}
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res = do_31div (a, __builtin_labs (b)).rem;
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return SIGNMULT (sign, res);
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}
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#endif /* L_modsi3 */
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#endif /* L_udivsi3 || L_divsi3 || L_umodsi3 || L_modsi3 */
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/*
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* Local variables:
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* eval: (c-set-style "gnu")
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* indent-tabs-mode: t
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* End:
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*/
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