202 lines
6.4 KiB
ArmAsm
202 lines
6.4 KiB
ArmAsm
.file "trunc.s"
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// Copyright (C) 2000, 2001, Intel Corporation
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// All rights reserved.
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//
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// Contributed 7/7/2000 by John Harrison, Cristina Iordache, Ted Kubaska,
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// Bob Norin, Shane Story, and Ping Tak Peter Tang of the
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// Computational Software Lab, Intel Corporation.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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//
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// * Redistributions in binary form must reproduce the above copyright
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// notice, this list of conditions and the following disclaimer in the
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// documentation and/or other materials provided with the distribution.
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//
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// * The name of Intel Corporation may not be used to endorse or promote
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// products derived from this software without specific prior written
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// permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL INTEL OR ITS
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// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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// OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY OR TORT (INCLUDING
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// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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//
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// Intel Corporation is the author of this code, and requests that all
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// problem reports or change requests be submitted to it directly at
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// http://developer.intel.com/opensource.
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//
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.align 32
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.global trunc#
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.section .text
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.proc trunc#
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.align 32
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// History
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//==============================================================
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// 7/7/00: Created
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//==============================================================
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// API
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//==============================================================
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// double trunc(double x)
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//==============================================================
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#include "libm_support.h"
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// general input registers:
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TRUNC_GR_FFFF = r14
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TRUNC_GR_signexp = r15
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TRUNC_GR_exponent = r16
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TRUNC_GR_expmask = r17
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TRUNC_GR_bigexp = r18
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// floating-point registers:
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// f8, f9, f11, f12
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// predicate registers used:
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// p6, p7, p8, p9, p10, p11
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// Overview of operation
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//==============================================================
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// double trunc(double x)
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// Return an integer value (represented as a double) less than or
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// equal to x in magnitude.
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// This is x rounded toward zero to an integral value.
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//==============================================================
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// double_extended
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// if the exponent is > 1003e => 3F(true) = 63(decimal)
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// we have a significand of 64 bits 1.63-bits.
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// If we multiply by 2^63, we no longer have a fractional part
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// So input is an integer value already.
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// double
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// if the exponent is >= 10033 => 34(true) = 52(decimal)
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// 34 + 3ff = 433
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// we have a significand of 53 bits 1.52-bits. (implicit 1)
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// If we multiply by 2^52, we no longer have a fractional part
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// So input is an integer value already.
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// single
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// if the exponent is > 10016 => 17(true) = 23(decimal)
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// we have a significand of 24 bits 1.23-bits. (implicit 1)
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// If we multiply by 2^23, we no longer have a fractional part
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// So input is an integer value already.
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trunc:
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{ .mfi
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getf.exp TRUNC_GR_signexp = f8
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fcvt.fx.trunc.s1 f9 = f8
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addl TRUNC_GR_bigexp = 0x10033, r0
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}
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{ .mfi
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mov TRUNC_GR_FFFF = 0x0FFFF
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fnorm.d f11 = f8
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mov TRUNC_GR_expmask = 0x1FFFF
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};;
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// get the exponent of x
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// convert x to integer in signficand of f9
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// Normalize x - this will raise invalid on SNaNs, the
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// denormal operand flag - and possibly a spurious U flag
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// get exponent only mask (will exclude sign bit)
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{ .mfi
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nop.m 0
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fclass.m p7,p8 = f8, 0x0b
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nop.i 0
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}
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{ .mfi
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nop.m 0
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fcmp.eq.unc.s1 p9,p0 = f8,f0
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nop.i 0
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};;
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// fclass to set p7 if unnorm
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{ .mmi
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and TRUNC_GR_exponent = TRUNC_GR_signexp, TRUNC_GR_expmask ;;
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(p8) cmp.ge.unc p10,p11 = TRUNC_GR_exponent, TRUNC_GR_bigexp
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(p8) cmp.ne.unc p6,p0 = TRUNC_GR_exponent, TRUNC_GR_signexp
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};;
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// Get the exponent of x
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// Test if exponent such that result already an integer
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// Test if x < 0
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{ .mmi
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(p9) cmp.eq.andcm p10,p11 = r0, r0
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(p6) cmp.lt.unc p6,p0 = TRUNC_GR_exponent, TRUNC_GR_FFFF
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nop.i 0
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};;
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// If -1 < x < 0, set p6, turn off p10 and p11, and set result to -0.0
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{ .mfb
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(p6) cmp.eq.andcm p10,p11 = r0, r0
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(p6) fmerge.s f8 = f8, f0
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nop.b 0
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};;
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// If not a unnorm, set p10 if x already is a big int, nan, or inf?
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// If not a unnorm, set p10 if x already is a big int, nan, or inf?
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.pred.rel "mutex",p10,p11
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{ .mfb
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nop.m 0
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(p11) fcvt.xf f8 = f9
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nop.b 0
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}
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{ .mfb
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nop.m 0
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(p10) fma.d.s1 f8 = f11,f1,f0
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(p8) br.ret.sptk b0
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};;
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// If not a unnorm and not an big int, nan,or +/-inf convert signficand
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// back to f8.
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// If not a unorm and a big int, nan, or +/-inf, return fnorm'd x
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// If not a unorm, Return
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// If unnorm, get the exponent again - perhaps it wasn't a denorm.
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{ .mfb
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(p7) getf.exp TRUNC_GR_signexp = f11
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(p7) fcvt.fx.trunc.s1 f12 = f11
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nop.b 0
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};;
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{ .mfb
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and TRUNC_GR_exponent = TRUNC_GR_signexp, TRUNC_GR_expmask
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fcmp.lt.unc.s1 p9,p0 = f8,f0
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nop.b 0
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};;
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{ .mfb
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cmp.ge.unc p10,p11 = TRUNC_GR_exponent, TRUNC_GR_bigexp
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nop.f 0
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nop.b 0
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};;
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// If a unnorm, check to see if value is already a big int.
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{ .mfb
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nop.m 0
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(p11) fcvt.xf f8 = f12
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nop.b 0
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}
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{ .mfi
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nop.m 0
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(p10) fma.d.s1 f8 = f11,f1,f0
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nop.i 0
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};;
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{ .mfb
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nop.m 0
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(p9) fmerge.ns f8 = f1,f8
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br.ret.sptk b0
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};;
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// If so return it. Otherwise, return (fcvt.xf(fcvt.fx.trunc(x)))
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// Make sure the result is negative if it should be - that is
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// negative(denormal) -> -0.
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.endp trunc
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ASM_SIZE_DIRECTIVE(trunc)
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