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.file "round.s"
// Copyright (C) 2000, 2001, Intel Corporation
// All rights reserved.
//
// Contributed 10/25/2000 by John Harrison, Cristina Iordache, Ted Kubaska,
// Bob Norin, Tom Rowan, Shane Story, and Ping Tak Peter Tang of the
// Computational Software Lab, Intel Corporation.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// * The name of Intel Corporation may not be used to endorse or promote
// products derived from this software without specific prior written
// permission.
//
// 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.
//
// History
//==============================================================
// 10/25/2000: Created
//==============================================================
//
// API
//==============================================================
// double round(double x)
//
#include "libm_support.h"
// general input registers:
//
round_GR_half = r14
round_GR_big = r15
round_GR_expmask = r16
round_GR_signexp = r17
round_GR_exp = r18
round_GR_expdiff = r19
// predicate registers used:
// p6 - p10
// floating-point registers used:
ROUND_NORM_f8 = f9
ROUND_TRUNC_f8 = f10
ROUND_RINT_f8 = f11
ROUND_FLOAT_TRUNC_f8 = f12
ROUND_FLOAT_RINT_f8 = f13
ROUND_REMAINDER = f14
ROUND_HALF = f15
// Overview of operation
//==============================================================
// double round(double x)
// Return an integer value (represented as a double) that is x
// rounded to nearest integer, halfway cases rounded away from
// zero.
// if x>0 result = trunc(x+0.5)
// if x<0 result = trunc(x-0.5)
// *******************************************************************************
// Set denormal flag for denormal input and
// and take denormal fault if necessary.
// If x is NAN, ZERO, INFINITY, or >= 2^52 then return
// qnan snan inf norm unorm 0 -+
// 1 1 1 0 0 1 11 0xe7
.align 32
.global round#
.section .text
.proc round#
.align 32
round:
// Get exponent for +0.5
// Truncate x to integer
{ .mfi
addl round_GR_half = 0x0fffe, r0
fcvt.fx.trunc.s1 ROUND_TRUNC_f8 = f8
nop.i 999
}
// Get signexp of x
// Normalize input
// Form exponent mask
{ .mfi
getf.exp round_GR_signexp = f8
fnorm ROUND_NORM_f8 = f8
addl round_GR_expmask = 0x1ffff, r0 ;;
}
// Form +0.5
// Round x to integer
{ .mfi
setf.exp ROUND_HALF = round_GR_half
fcvt.fx.s1 ROUND_RINT_f8 = f8
nop.i 999 ;;
}
// Get exp of x
// Test for NAN, INF, ZERO
// Get exponent at which input has no fractional part
{ .mfi
and round_GR_exp = round_GR_expmask, round_GR_signexp
fclass.m p8,p9 = f8,0xe7
addl round_GR_big = 0x10033, r0 ;;
}
// Get exp-bigexp
// If exp is so big there is no fractional part, then turn on p8, off p9
{ .mmi
sub round_GR_expdiff = round_GR_exp, round_GR_big ;;
#ifdef _LIBC
(p9) cmp.lt.or.andcm p8,p9 = r0, round_GR_expdiff
#else
(p9) cmp.ge.or.andcm p8,p9 = round_GR_expdiff, r0
#endif
nop.i 999 ;;
}
// Set p6 if x<0, else set p7
{ .mfi
nop.m 999
(p9) fcmp.lt.unc p6,p7 = f8,f0
nop.i 999
}
// If NAN, INF, ZERO, or no fractional part, result is just normalized input
{ .mfi
nop.m 999
(p8) fnorm.d.s0 f8 = f8
nop.i 999 ;;
}
// Float the truncated integer
{ .mfi
nop.m 999
(p9) fcvt.xf ROUND_FLOAT_TRUNC_f8 = ROUND_TRUNC_f8
nop.i 999 ;;
}
// Float the rounded integer to get preliminary result
{ .mfi
nop.m 999
(p9) fcvt.xf ROUND_FLOAT_RINT_f8 = ROUND_RINT_f8
nop.i 999 ;;
}
// If x<0 and the difference of the truncated input minus the input is 0.5
// then result = truncated input - 1.0
// Else if x>0 and the difference of the input minus truncated input is 0.5
// then result = truncated input + 1.0
// Else
// result = rounded input
// Endif
{ .mfi
nop.m 999
(p6) fsub.s1 ROUND_REMAINDER = ROUND_FLOAT_TRUNC_f8, ROUND_NORM_f8
nop.i 999
}
{ .mfi
nop.m 999
(p7) fsub.s1 ROUND_REMAINDER = ROUND_NORM_f8, ROUND_FLOAT_TRUNC_f8
nop.i 999 ;;
}
// Assume preliminary result is rounded integer
{ .mfi
nop.m 999
(p9) fnorm.d.s0 f8 = ROUND_FLOAT_RINT_f8
nop.i 999
}
// If x<0, test if result=0
{ .mfi
nop.m 999
(p6) fcmp.eq.unc p10,p0 = ROUND_FLOAT_RINT_f8,f0
nop.i 999 ;;
}
// If x<0 and result=0, set result=-0
{ .mfi
nop.m 999
(p10) fmerge.ns f8 = f1,f8
nop.i 999
}
// If x<0, test if remainder=0.5
{ .mfi
nop.m 999
(p6) fcmp.eq.unc p6,p0 = ROUND_REMAINDER, ROUND_HALF
nop.i 999 ;;
}
// If x>0, test if remainder=0.5
{ .mfi
nop.m 999
(p7) fcmp.eq.unc p7,p0 = ROUND_REMAINDER, ROUND_HALF
nop.i 999 ;;
}
// If x<0 and remainder=0.5, result=truncated-1.0
// If x>0 and remainder=0.5, result=truncated+1.0
// Exit
.pred.rel "mutex",p6,p7
{ .mfi
nop.m 999
(p6) fsub.d.s0 f8 = ROUND_FLOAT_TRUNC_f8,f1
nop.i 999
}
{ .mfb
nop.m 999
(p7) fadd.d.s0 f8 = ROUND_FLOAT_TRUNC_f8,f1
br.ret.sptk b0 ;;
}
.endp round
ASM_SIZE_DIRECTIVE(round)
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