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.file "trunc.s"
// Copyright (c) 2000, 2001, Intel Corporation
// All rights reserved.
//
// Contributed 7/7/2000 by John Harrison, Cristina Iordache, Ted Kubaska,
// Bob Norin, Shane Story, and Ping Tak Peter Tang of the
// Computational Software Lab, Intel Corporation.
//
// WARRANTY DISCLAIMER
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL INTEL OR ITS
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
// OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Intel Corporation is the author of this code, and requests that all
// problem reports or change requests be submitted to it directly at
// http://developer.intel.com/opensource.
//
.align 32
.global trunc#
.section .text
.proc trunc#
.align 32
// History
//==============================================================
// 7/7/00: Created
//==============================================================
// API
//==============================================================
// double trunc(double x)
//==============================================================
#include "libm_support.h"
// general input registers:
TRUNC_GR_FFFF = r14
TRUNC_GR_signexp = r15
TRUNC_GR_exponent = r16
TRUNC_GR_expmask = r17
TRUNC_GR_bigexp = r18
// floating-point registers:
// f8, f9, f11, f12
// predicate registers used:
// p6, p7, p8, p9, p10, p11
// Overview of operation
//==============================================================
// double trunc(double x)
// Return an integer value (represented as a double) less than or
// equal to x in magnitude.
// This is x rounded toward zero to an integral value.
//==============================================================
// double_extended
// if the exponent is > 1003e => 3F(true) = 63(decimal)
// we have a significand of 64 bits 1.63-bits.
// If we multiply by 2^63, we no longer have a fractional part
// So input is an integer value already.
// double
// if the exponent is >= 10033 => 34(true) = 52(decimal)
// 34 + 3ff = 433
// we have a significand of 53 bits 1.52-bits. (implicit 1)
// If we multiply by 2^52, we no longer have a fractional part
// So input is an integer value already.
// single
// if the exponent is > 10016 => 17(true) = 23(decimal)
// we have a significand of 24 bits 1.23-bits. (implicit 1)
// If we multiply by 2^23, we no longer have a fractional part
// So input is an integer value already.
trunc:
{ .mfi
getf.exp TRUNC_GR_signexp = f8
fcvt.fx.trunc.s1 f9 = f8
addl TRUNC_GR_bigexp = 0x10033, r0
}
{ .mfi
mov TRUNC_GR_FFFF = 0x0FFFF
fnorm.d f11 = f8
mov TRUNC_GR_expmask = 0x1FFFF
};;
// get the exponent of x
// convert x to integer in signficand of f9
// Normalize x - this will raise invalid on SNaNs, the
// denormal operand flag - and possibly a spurious U flag
// get exponent only mask (will exclude sign bit)
{ .mfi
nop.m 0
fclass.m p7,p8 = f8, 0x0b
nop.i 0
}
{ .mfi
nop.m 0
fcmp.eq.unc.s1 p9,p0 = f8,f0
nop.i 0
};;
// fclass to set p7 if unnorm
{ .mmi
and TRUNC_GR_exponent = TRUNC_GR_signexp, TRUNC_GR_expmask ;;
(p8) cmp.ge.unc p10,p11 = TRUNC_GR_exponent, TRUNC_GR_bigexp
(p8) cmp.ne.unc p6,p0 = TRUNC_GR_exponent, TRUNC_GR_signexp
};;
// Get the exponent of x
// Test if exponent such that result already an integer
// Test if x < 0
{ .mmi
(p9) cmp.eq.andcm p10,p11 = r0, r0
(p6) cmp.lt.unc p6,p0 = TRUNC_GR_exponent, TRUNC_GR_FFFF
nop.i 0
};;
// If -1 < x < 0, set p6, turn off p10 and p11, and set result to -0.0
{ .mfb
(p6) cmp.eq.andcm p10,p11 = r0, r0
(p6) fmerge.s f8 = f8, f0
nop.b 0
};;
// If not a unnorm, set p10 if x already is a big int, nan, or inf?
// If not a unnorm, set p10 if x already is a big int, nan, or inf?
.pred.rel "mutex",p10,p11
{ .mfb
nop.m 0
(p11) fcvt.xf f8 = f9
nop.b 0
}
{ .mfb
nop.m 0
(p10) fma.d.s1 f8 = f11,f1,f0
(p8) br.ret.sptk b0
};;
// If not a unnorm and not an big int, nan,or +/-inf convert signficand
// back to f8.
// If not a unorm and a big int, nan, or +/-inf, return fnorm'd x
// If not a unorm, Return
// If unnorm, get the exponent again - perhaps it wasn't a denorm.
{ .mfb
(p7) getf.exp TRUNC_GR_signexp = f11
(p7) fcvt.fx.trunc.s1 f12 = f11
nop.b 0
};;
{ .mfb
and TRUNC_GR_exponent = TRUNC_GR_signexp, TRUNC_GR_expmask
fcmp.lt.unc.s1 p9,p0 = f8,f0
nop.b 0
};;
{ .mfb
cmp.ge.unc p10,p11 = TRUNC_GR_exponent, TRUNC_GR_bigexp
nop.f 0
nop.b 0
};;
// If a unnorm, check to see if value is already a big int.
{ .mfb
nop.m 0
(p11) fcvt.xf f8 = f12
nop.b 0
}
{ .mfi
nop.m 0
(p10) fma.d.s1 f8 = f11,f1,f0
nop.i 0
};;
{ .mfb
nop.m 0
(p9) fmerge.ns f8 = f1,f8
br.ret.sptk b0
};;
// If so return it. Otherwise, return (fcvt.xf(fcvt.fx.trunc(x)))
// Make sure the result is negative if it should be - that is
// negative(denormal) -> -0.
.endp trunc
ASM_SIZE_DIRECTIVE(trunc)
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