.file "erff.s"
// Copyright (c) 2001 - 2005, Intel Corporation
// All rights reserved.
//
// Contributed 2001 by the Intel Numerics Group, Intel Corporation
//
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// 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
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// 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://www.intel.com/software/products/opensource/libraries/num.htm.
//
// History
//==============================================================
// 08/14/01 Initial version
// 05/20/02 Cleaned up namespace and sf0 syntax
// 02/06/03 Reordered header: .section, .global, .proc, .align
// 03/31/05 Reformatted delimiters between data tables
//
// API
//==============================================================
// float erff(float)
//
// Overview of operation
//==============================================================
// Background
//
//
// There are 8 paths:
// 1. x = +/-0.0
// Return erff(x) = +/-0.0
//
// 2. 0.0 < |x| < 0.125
// Return erff(x) = x *Pol3(x^2),
// where Pol3(x^2) = C3*x^6 + C2*x^4 + C1*x^2 + C0
//
// 3. 0.125 <= |x| < 4.0
// Return erff(x) = sign(x)*PolD(x)*PolC(|x|) + sign(x)*PolA(|x|),
// where sign(x)*PolD(x) = sign(x)*(|x|^7 + D2*x^6 + D1*|x|^5 + D0*x^4),
// PolC(|x|) = B0*x^4 + C3*|x|^3 + C2*|x|^2 + C1*|x| + C0,
// PolA(|x|) = A3|x|^3 + A2*x^2 + A1*|x| + A0
//
// Actually range 0.125<=|x|< 4.0 is splitted to 5 subranges.
// For each subrange there is particular set of coefficients.
// Below is the list of subranges:
// 3.1 0.125 <= |x| < 0.25
// 3.2 0.25 <= |x| < 0.5
// 3.3 0.5 <= |x| < 1.0
// 3.4 1.0 <= |x| < 2.0
// 3.5 2.0 <= |x| < 4.0
//
// 4. 4.0 <= |x| < +INF
// Return erff(x) = sign(x)*(1.0d - 2^(-52))
//
// 5. |x| = INF
// Return erff(x) = sign(x) * 1.0
//
// 6. x = [S,Q]NaN
// Return erff(x) = QNaN
//
// 7. x is positive denormal
// Return erff(x) = C0*x - x^2,
// where C0 = 2.0/sqrt(Pi)
//
// 8. x is negative denormal
// Return erff(x) = C0*x + x^2,
// where C0 = 2.0/sqrt(Pi)
//
// Registers used
//==============================================================
// Floating Point registers used:
// f8, input
// f32 -> f59
// General registers used:
// r32 -> r45, r2, r3
// Predicate registers used:
// p0, p6 -> p12, p14, p15
// p6 to filter out case when x = [Q,S]NaN or +/-0
// p7 to filter out case when x = denormal
// p8 set if |x| >= 0.3125, used also to process denormal input
// p9 to filter out case when |x| = inf
// p10 to filter out case when |x| < 0.125
// p11 to filter out case when 0.125 <= |x| < 4.0
// p12 to filter out case when |x| >= 4.0
// p14 set to 1 for positive x
// p15 set to 1 for negative x
// Assembly macros
//==============================================================
rDataPtr = r2
rDataPtr1 = r3
rBias = r33
rCoeffAddr3 = r34
rCoeffAddr1 = r35
rCoeffAddr2 = r36
rOffset2 = r37
rBias2 = r38
rMask = r39
rArg = r40
rBound = r41
rSignBit = r42
rAbsArg = r43
rDataPtr2 = r44
rSaturation = r45
//==============================================================
fA0 = f32
fA1 = f33
fA2 = f34
fA3 = f35
fC0 = f36
fC1 = f37
fC2 = f38
fC3 = f39
fD0 = f40
fD1 = f41
fD2 = f42
fB0 = f43
fArgSqr = f44
fAbsArg = f45
fSignumX = f46
fArg4 = f47
fArg4Sgn = f48
fArg3 = f49
fArg3Sgn = f50
fArg7Sgn = f51
fArg6Sgn = f52
fPolC = f53
fPolCTmp = f54
fPolA = f55
fPolATmp = f56
fPolD = f57
fPolDTmp = f58
fArgSqrSgn = f59
// Data tables
//==============================================================
RODATA
.align 16
LOCAL_OBJECT_START(erff_data)
// Polynomial coefficients for the erf(x), 0.125 <= |x| < 0.25
data8 0xBE4218BB56B49E66 // C0
data8 0x3F7AFB8315DA322B // C1
data8 0x3F615D6EBEE0CA32 // C2
data8 0xBF468D71CF4F0918 // C3
data8 0x40312115B0932F24 // D0
data8 0xC0160D6CD0991EA3 // D1
data8 0xBFE04A567A6DBE4A // D2
data8 0xBF4207BC640D1509 // B0
// Polynomial coefficients for the erf(x), 0.25 <= |x| < 0.5
data8 0x3F90849356383F58 // C0
data8 0x3F830BD5BA240F09 // C1
data8 0xBF3FA4970E2BCE23 // C2
data8 0xBF6061798E58D0FD // C3
data8 0xBF68C0D83DD22E02 // D0
data8 0x401C0A9EE4108F94 // D1
data8 0xC01056F9B5E387F5 // D2
data8 0x3F1C9744E36A5706 // B0
// Polynomial coefficients for the erf(x), 0.5 <= |x| < 1.0
data8 0x3F85F7D419A13DE3 // C0
data8 0x3F791A13FF66D45A // C1
data8 0x3F46B17B16B5929F // C2
data8 0xBF5124947A8BF45E // C3
data8 0x3FA1B3FD95EA9564 // D0
data8 0x40250CECD79A020A // D1
data8 0xC0190DC96FF66CCD // D2
data8 0x3F4401AE28BA4DD5 // B0
// Polynomial coefficients for the erf(x), 1.0 <= |x| < 2.0
data8 0xBF49E07E3584C3AE // C0
data8 0x3F3166621131445C // C1
data8 0xBF65B7FC1EAC2099 // C2
data8 0x3F508C6BD211D736 // C3
data8 0xC053FABD70601067 // D0
data8 0x404A06640EE87808 // D1
data8 0xC0283F30817A3F08 // D2
data8 0xBF2F6DBBF4D6257F // B0
// Polynomial coefficients for the erf(x), 2.0 <= |x| < 4.0
data8 0xBF849855D67E9407 // C0
data8 0x3F5ECA5FEC01C70C // C1
data8 0xBF483110C30FABA4 // C2
data8 0x3F1618DA72860403 // C3
data8 0xC08A5C9D5FE8B9F6 // D0
data8 0x406EFF5F088CEC4B // D1
data8 0xC03A5743DF38FDE0 // D2
data8 0xBEE397A9FA5686A2 // B0
// Polynomial coefficients for the erf(x), -0.125 < x < 0.125
data8 0x3FF20DD7504270CB // C0
data8 0xBFD8127465AFE719 // C1
data8 0x3FBCE2D77791DD77 // C2
data8 0xBF9B582755CDF345 // C3
// Polynomial coefficients for the erf(x), 0.125 <= |x| < 0.25
data8 0xBD54E7E451AF0E36 // A0
data8 0x3FF20DD75043FE20 // A1
data8 0xBE05680ACF8280E4 // A2
data8 0xBFD812745E92C3D3 // A3
// Polynomial coefficients for the erf(x), 0.25 <= |x| < 0.5
data8 0xBE1ACEC2859CB55F // A0
data8 0x3FF20DD75E8D2B64 // A1
data8 0xBEABC6A83208FCFC // A2
data8 0xBFD81253E42E7B99 // A3
// Polynomial coefficients for the erf(x), 0.5 <= |x| < 1.0
data8 0x3EABD5A2482B4979 // A0
data8 0x3FF20DCAA52085D5 // A1
data8 0x3F13A994A348795B // A2
data8 0xBFD8167B2DFCDE44 // A3
// Polynomial coefficients for the erf(x), 1.0 <= |x| < 2.0
data8 0xBF5BA377DDAB4E17 // A0
data8 0x3FF2397F1D8FC0ED // A1
data8 0xBF9945BFC1915C21 // A2
data8 0xBFD747AAABB690D8 // A3
// Polynomial coefficients for the erf(x), 2.0 <= |x| < 4.0
data8 0x3FF0E2920E0391AF // A0
data8 0xC00D249D1A95A5AE // A1
data8 0x40233905061C3803 // A2
data8 0xC027560B851F7690 // A3
//
data8 0x3FEFFFFFFFFFFFFF // 1.0 - epsilon
data8 0x3FF20DD750429B6D // C0 = 2.0/sqrt(Pi)
LOCAL_OBJECT_END(erff_data)
.section .text
GLOBAL_LIBM_ENTRY(erff)
{ .mfi
alloc r32 = ar.pfs, 0, 14, 0, 0
fmerge.s fAbsArg = f1, f8 // |x|
addl rMask = 0x806, r0
}
{ .mfi
addl rDataPtr = @ltoff(erff_data), gp
fma.s1 fArgSqr = f8, f8, f0 // x^2
adds rSignBit = 0x1, r0
}
;;
{ .mfi
getf.s rArg = f8 // x in GR
fclass.m p7,p0 = f8, 0x0b // is x denormal ?
// sign bit and 2 most bits in significand
shl rMask = rMask, 20
}
{ .mfi
ld8 rDataPtr = [rDataPtr]
nop.f 0
adds rBias2 = 0x1F0, r0
}
;;
{ .mfi
nop.m 0
fmerge.s fSignumX = f8, f1 // signum(x)
shl rSignBit = rSignBit, 31 // mask for sign bit
}
{ .mfi
adds rBound = 0x3E0, r0
nop.f 0
adds rSaturation = 0x408, r0
}
;;
{ .mfi
andcm rOffset2 = rArg, rMask
fclass.m p6,p0 = f8, 0xc7 // is x [S,Q]NaN or +/-0 ?
shl rBound = rBound, 20 // 0.125f in GR
}
{ .mfb
andcm rAbsArg = rArg, rSignBit // |x| in GR
nop.f 0
(p7) br.cond.spnt erff_denormal // branch out if x is denormal
}
;;
{ .mfi
adds rCoeffAddr2 = 352, rDataPtr
fclass.m p9,p0 = f8, 0x23 // is x +/- inf?
shr rOffset2 = rOffset2, 21
}
{ .mfi
cmp.lt p10, p8 = rAbsArg, rBound // |x| < 0.125?
nop.f 0
adds rCoeffAddr3 = 16, rDataPtr
}
;;
{ .mfi
(p8) sub rBias = rOffset2, rBias2
fma.s1 fArg4 = fArgSqr, fArgSqr, f0 // x^4
shl rSaturation = rSaturation, 20// 4.0 in GR (saturation bound)
}
{ .mfb
(p10) adds rBias = 0x14, r0
(p6) fma.s.s0 f8 = f8,f1,f8 // NaN or +/-0
(p6) br.ret.spnt b0 // exit for x = NaN or +/-0
}
;;
{ .mfi
shladd rCoeffAddr1 = rBias, 4, rDataPtr
fma.s1 fArg3Sgn = fArgSqr, f8, f0 // sign(x)*|x|^3
// is |x| < 4.0?
cmp.lt p11, p12 = rAbsArg, rSaturation
}
{ .mfi
shladd rCoeffAddr3 = rBias, 4, rCoeffAddr3
fma.s1 fArg3 = fArgSqr, fAbsArg, f0 // |x|^3
shladd rCoeffAddr2 = rBias, 3, rCoeffAddr2
}
;;
{ .mfi
(p11) ldfpd fC0, fC1 = [rCoeffAddr1]
(p9) fmerge.s f8 = f8,f1 // +/- inf
(p12) adds rDataPtr = 512, rDataPtr
}
{ .mfb
(p11) ldfpd fC2, fC3 = [rCoeffAddr3], 16
nop.f 0
(p9) br.ret.spnt b0 // exit for x = +/- inf
}
;;
{ .mfi
(p11) ldfpd fA0, fA1 = [rCoeffAddr2], 16
nop.f 0
nop.i 0
}
{ .mfi
add rCoeffAddr1 = 48, rCoeffAddr1
nop.f 0
nop.i 0
}
;;
{ .mfi
(p11) ldfpd fD0, fD1 = [rCoeffAddr3]
nop.f 0
nop.i 0
}
{ .mfb
(p11) ldfpd fD2, fB0 = [rCoeffAddr1]
// sign(x)*|x|^2
fma.s1 fArgSqrSgn = fArgSqr, fSignumX, f0
(p10) br.cond.spnt erff_near_zero
}
;;
{ .mfi
(p11) ldfpd fA2, fA3 = [rCoeffAddr2], 16
fcmp.lt.s1 p15, p14 = f8,f0
nop.i 0
}
{ .mfb
(p12) ldfd fA0 = [rDataPtr]
fma.s1 fArg4Sgn = fArg4, fSignumX, f0 // sign(x)*|x|^4
(p12) br.cond.spnt erff_saturation
}
;;
{ .mfi
nop.m 0
fma.s1 fArg7Sgn = fArg4, fArg3Sgn, f0 // sign(x)*|x|^7
nop.i 0
}
{ .mfi
nop.m 0
fma.s1 fArg6Sgn = fArg3, fArg3Sgn, f0 // sign(x)*|x|^6
nop.i 0
}
;;
{ .mfi
nop.m 0
fma.s1 fPolC = fC3, fAbsArg, fC2 // C3*|x| + C2
nop.i 0
}
{ .mfi
nop.m 0
fma.s1 fPolCTmp = fC1, fAbsArg, fC0 // C1*|x| + C0
nop.i 0
};;
{ .mfi
nop.m 0
fma.s1 fPolA = fA1, fAbsArg, fA0 // A1*|x| + A0
nop.i 0
}
;;
{ .mfi
nop.m 0
fma.s1 fPolD = fD1, fAbsArg, fD0 // D1*|x| + D0
nop.i 0
}
{ .mfi
nop.m 0
// sign(x)*(|x|^7 + D2*x^6)
fma.s1 fPolDTmp = fArg6Sgn, fD2, fArg7Sgn
nop.i 0
};;
{ .mfi
nop.m 0
fma.s1 fPolATmp = fA3, fAbsArg, fA2 // A3*|x| + A2
nop.i 0
}
{ .mfi
nop.m 0
fma.s1 fB0 = fB0, fArg4, f0 // B0*x^4
nop.i 0
};;
{ .mfi
nop.m 0
// C3*|x|^3 + C2*x^2 + C1*|x| + C0
fma.s1 fPolC = fPolC, fArgSqr, fPolCTmp
nop.i 0
}
;;
{ .mfi
nop.m 0
// PolD = sign(x)*(|x|^7 + D2*x^6 + D1*|x|^5 + D0*x^4)
fma.d.s1 fPolD = fPolD, fArg4Sgn, fPolDTmp
nop.i 0
}
;;
{ .mfi
nop.m 0
// PolA = A3|x|^3 + A2*x^2 + A1*|x| + A0
fma.d.s1 fPolA = fPolATmp, fArgSqr, fPolA
nop.i 0
}
;;
{ .mfi
nop.m 0
// PolC = B0*x^4 + C3*|x|^3 + C2*|x|^2 + C1*|x| + C0
fma.d.s1 fPolC = fPolC, f1, fB0
nop.i 0
}
;;
{ .mfi
nop.m 0
(p14) fma.s.s0 f8 = fPolC, fPolD, fPolA // for positive x
nop.i 0
}
{ .mfb
nop.m 0
(p15) fms.s.s0 f8 = fPolC, fPolD, fPolA // for negative x
br.ret.sptk b0 // Exit for 0.125 <=|x|< 4.0
};;
// Here if |x| < 0.125
erff_near_zero:
{ .mfi
nop.m 0
fma.s1 fPolC = fC3, fArgSqr, fC2 // C3*x^2 + C2
nop.i 0
}
{ .mfi
nop.m 0
fma.s1 fPolCTmp = fC1, fArgSqr, fC0 // C1*x^2 + C0
nop.i 0
};;
{ .mfi
nop.m 0
fma.s1 fPolC = fPolC, fArg4, fPolCTmp // C3*x^6 + C2*x^4 + C1*x^2 + C0
nop.i 0
};;
{ .mfb
nop.m 0
// x*(C3*x^6 + C2*x^4 + C1*x^2 + C0)
fma.s.s0 f8 = fPolC, f8, f0
br.ret.sptk b0 // Exit for |x| < 0.125
};;
// Here if 4.0 <= |x| < +inf
erff_saturation:
{ .mfb
nop.m 0
fma.s.s0 f8 = fA0, fSignumX, f0 // sign(x)*(1.0d - 2^(-52))
// Exit for 4.0 <= |x| < +inf
br.ret.sptk b0 // Exit for 4.0 <=|x|< +inf
}
;;
// Here if x is single precision denormal
erff_denormal:
{ .mfi
adds rDataPtr = 520, rDataPtr // address of C0
fclass.m p7,p8 = f8, 0x0a // is x -denormal ?
nop.i 0
}
;;
{ .mfi
ldfd fC0 = [rDataPtr] // C0
nop.f 0
nop.i 0
}
;;
{ .mfi
nop.m 0
fma.s1 fC0 = fC0,f8,f0 // C0*x
nop.i 0
}
;;
{ .mfi
nop.m 0
(p7) fma.s.s0 f8 = f8,f8,fC0 // -denormal
nop.i 0
}
{ .mfb
nop.m 0
(p8) fnma.s.s0 f8 = f8,f8,fC0 // +denormal
br.ret.sptk b0 // Exit for denormal
}
;;
GLOBAL_LIBM_END(erff)
libm_alias_float_other (erf, erf)