.file "acos.s"

// Copyright (c) 2000 - 2003 Intel Corporation

// All rights reserved.

//

// Contributed 2000 by the Intel Numerics Group, 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://www.intel.com/software/products/opensource/libraries/num.htm.

// History

//==============================================================

// 02/02/00 Initial version

// 08/17/00 New and much faster algorithm.

// 08/30/00 Avoided bank conflicts on loads, shortened |x|=1 and x=0 paths,

//          fixed mfb split issue stalls.

// 05/20/02 Cleaned up namespace and sf0 syntax

// 08/02/02 New and much faster algorithm II

// 02/06/03 Reordered header: .section, .global, .proc, .align

// Description

//=========================================

// The acos function computes the principal value of the arc cosine of x.

// acos(0) returns Pi/2, acos(1) returns 0, acos(-1) returns Pi.

// A doman error occurs for arguments not in the range [-1,+1].

//

// The acos function returns the arc cosine in the range [0, Pi] radians.

//

// There are 8 paths:

// 1. x = +/-0.0

//    Return acos(x) = Pi/2 + x

//

// 2. 0.0 < |x| < 0.625

//    Return acos(x) = Pi/2 - x - x^3 *PolA(x^2)

//    where PolA(x^2) = A3 + A5*x^2 + A7*x^4 +...+ A35*x^32

//

// 3. 0.625 <=|x| < 1.0

//    Return acos(x) = Pi/2 - asin(x) =

//                   = Pi/2 - sign(x) * ( Pi/2 - sqrt(R) * PolB(R))

//    Where R = 1 - |x|,

//          PolB(R) = B0 + B1*R + B2*R^2 +...+B12*R^12

//

//    sqrt(R) is approximated using the following sequence:

//        y0 = (1 + eps)/sqrt(R) - initial approximation by frsqrta,

//             |eps| < 2^(-8)

//        Then 3 iterations are used to refine the result:

//        H0 = 0.5*y0

//        S0 = R*y0

//

//        d0 = 0.5 - H0*S0

//        H1 = H0 + d0*H0

//        S1 = S0 + d0*S0

//

//        d1 = 0.5 - H1*S1

//        H2 = H1 + d0*H1

//        S2 = S1 + d0*S1

//

//        d2 = 0.5 - H2*S2

//        S3 = S3 + d2*S3

//

//        S3 approximates sqrt(R) with enough accuracy for this algorithm

//

//    So, the result should be reconstracted as follows:

//    acos(x) = Pi/2 - sign(x) * (Pi/2 - S3*PolB(R))

//

//    But for optimization purposes the reconstruction step is slightly

//    changed:

//    acos(x) = Cpi + sign(x)*PolB(R)*S2 - sign(x)*d2*S2*PolB(R)

//        where Cpi = 0 if x > 0 and Cpi = Pi if x < 0

//

// 4. |x| = 1.0

//    Return acos(1.0) = 0.0, acos(-1.0) = Pi

//

// 5. 1.0 < |x| <= +INF

//    A doman error occurs for arguments not in the range [-1,+1]

//

// 6. x = [S,Q]NaN

//    Return acos(x) = QNaN

//

// 7. x is denormal

//    Return acos(x) = Pi/2 - x,

//

// 8. x is unnormal

//    Normalize input in f8 and return to the very beginning of the function

//

// Registers used

//==============================================================

// Floating Point registers used:

// f8, input, output

// f6, f7, f9 -> f15, f32 -> f64

// General registers used:

// r3, r21 -> r31, r32 -> r38

// Predicate registers used:

// p0, p6 -> p14

//

// Assembly macros

//=========================================

// integer registers used

// scratch

rTblAddr                      = r3

rPiBy2Ptr                     = r21

rTmpPtr3                      = r22

rDenoBound                    = r23

rOne                          = r24

rAbsXBits                     = r25

rHalf                         = r26

r0625                         = r27

rSign                         = r28

rXBits                        = r29

rTmpPtr2                      = r30

rTmpPtr1                      = r31

// stacked

GR_SAVE_PFS                   = r32

GR_SAVE_B0                    = r33

GR_SAVE_GP                    = r34

GR_Parameter_X                = r35

GR_Parameter_Y                = r36

GR_Parameter_RESULT           = r37

GR_Parameter_TAG              = r38

// floating point registers used

FR_X                          = f10

FR_Y                          = f1

FR_RESULT                     = f8

// scratch

fXSqr                         = f6

fXCube                        = f7

fXQuadr                       = f9

f1pX                          = f10

f1mX                          = f11

f1pXRcp                       = f12

f1mXRcp                       = f13

fH                            = f14

fS                            = f15

// stacked

fA3                           = f32

fB1                           = f32

fA5                           = f33

fB2                           = f33

fA7                           = f34

fPiBy2                        = f34

fA9                           = f35

fA11                          = f36

fB10                          = f35

fB11                          = f36

fA13                          = f37

fA15                          = f38

fB4                           = f37

fB5                           = f38

fA17                          = f39

fA19                          = f40

fB6                           = f39

fB7                           = f40

fA21                          = f41

fA23                          = f42

fB3                           = f41

fB8                           = f42

fA25                          = f43

fA27                          = f44

fB9                           = f43

fB12                          = f44

fA29                          = f45

fA31                          = f46

fA33                          = f47

fA35                          = f48

fBaseP                        = f49

fB0                           = f50

fSignedS                      = f51

fD                            = f52

fHalf                         = f53

fR                            = f54

fCloseTo1Pol                  = f55

fSignX                        = f56

fDenoBound                    = f57

fNormX                        = f58

fX8                           = f59

fRSqr                         = f60

fRQuadr                       = f61

fR8                           = f62

fX16                          = f63

fCpi                          = f64

// Data tables

//==============================================================

RODATA

.align 16

LOCAL_OBJECT_START(acos_base_range_table)

// Ai: Polynomial coefficients for the acos(x), |x| < .625000

// Bi: Polynomial coefficients for the acos(x), |x| > .625000

data8 0xBFDAAB56C01AE468 //A29

data8 0x3FE1C470B76A5B2B //A31

data8 0xBFDC5FF82A0C4205 //A33

data8 0x3FC71FD88BFE93F0 //A35

data8 0xB504F333F9DE6487, 0x00003FFF //B0

data8 0xAAAAAAAAAAAAFC18, 0x00003FFC //A3

data8 0x3F9F1C71BC4A7823 //A9

data8 0x3F96E8BBAAB216B2 //A11

data8 0x3F91C4CA1F9F8A98 //A13

data8 0x3F8C9DDCEDEBE7A6 //A15

data8 0x3F877784442B1516 //A17

data8 0x3F859C0491802BA2 //A19

data8 0x9999999998C88B8F, 0x00003FFB //A5

data8 0x3F6BD7A9A660BF5E //A21

data8 0x3F9FC1659340419D //A23

data8 0xB6DB6DB798149BDF, 0x00003FFA //A7

data8 0xBFB3EF18964D3ED3 //A25

data8 0x3FCD285315542CF2 //A27

data8 0xF15BEEEFF7D2966A, 0x00003FFB //B1

data8 0x3EF0DDA376D10FB3 //B10

data8 0xBEB83CAFE05EBAC9 //B11

data8 0x3F65FFB67B513644 //B4

data8 0x3F5032FBB86A4501 //B5

data8 0x3F392162276C7CBA //B6

data8 0x3F2435949FD98BDF //B7

data8 0xD93923D7FA08341C, 0x00003FF9 //B2

data8 0x3F802995B6D90BDB //B3

data8 0x3F10DF86B341A63F //B8

data8 0xC90FDAA22168C235, 0x00003FFF // Pi/2

data8 0x3EFA3EBD6B0ECB9D //B9

data8 0x3EDE18BA080E9098 //B12

LOCAL_OBJECT_END(acos_base_range_table)

.section .text

GLOBAL_LIBM_ENTRY(acos)

acos_unnormal_back:

{ .mfi

      getf.d             rXBits = f8 // grab bits of input value

      // set p12 = 1 if x is a NaN, denormal, or zero

      fclass.m           p12, p0 = f8, 0xcf

      adds               rSign = 1, r0

}

{ .mfi

      addl               rTblAddr = @ltoff(acos_base_range_table),gp

      // 1 - x = 1 - |x| for positive x

      fms.s1             f1mX = f1, f1, f8

      addl               rHalf = 0xFFFE, r0 // exponent of 1/2

}

;;

{ .mfi

      addl               r0625 = 0x3FE4, r0 // high 16 bits of 0.625

      // set p8 = 1 if x < 0

      fcmp.lt.s1         p8, p9 = f8, f0

      shl                rSign = rSign, 63 // sign bit

}

{ .mfi

      // point to the beginning of the table

      ld8                rTblAddr = [rTblAddr]

      // 1 + x = 1 - |x| for negative x

      fma.s1             f1pX = f1, f1, f8

      adds               rOne = 0x3FF, r0

}

;;

{ .mfi

      andcm              rAbsXBits = rXBits, rSign // bits of |x|

      fmerge.s           fSignX = f8, f1 // signum(x)

      shl                r0625 = r0625, 48 // bits of DP representation of 0.625

}

{ .mfb

      setf.exp           fHalf = rHalf // load A2 to FP reg

      fma.s1             fXSqr = f8, f8, f0 // x^2

      // branch on special path if x is a NaN, denormal, or zero

(p12) br.cond.spnt       acos_special

}

;;

{ .mfi

      adds               rPiBy2Ptr = 272, rTblAddr

      nop.f              0

      shl                rOne = rOne, 52 // bits of 1.0

}

{ .mfi

      adds               rTmpPtr1 = 16, rTblAddr

      nop.f              0

      // set p6 = 1 if |x| < 0.625

      cmp.lt             p6, p7 = rAbsXBits, r0625

}

;;

{ .mfi

      ldfpd              fA29, fA31 = [rTblAddr] // A29, fA31

      // 1 - x = 1 - |x| for positive x

(p9)  fms.s1             fR = f1, f1, f8

      // point to coefficient of "near 1" polynomial

(p7)  adds               rTmpPtr2 = 176, rTblAddr

}

{ .mfi

      ldfpd              fA33, fA35 = [rTmpPtr1], 16 // A33, fA35

      // 1 + x = 1 - |x| for negative x

(p8)  fma.s1             fR = f1, f1, f8

(p6)  adds               rTmpPtr2 = 48, rTblAddr

}

;;

{ .mfi

      ldfe               fB0 = [rTmpPtr1], 16 // B0

      nop.f              0

      nop.i              0

}

{ .mib

      adds               rTmpPtr3 = 16, rTmpPtr2

      // set p10 = 1 if |x| = 1.0

      cmp.eq             p10, p0 = rAbsXBits, rOne

      // branch on special path for |x| = 1.0

(p10) br.cond.spnt       acos_abs_1

}

;;

{ .mfi

      ldfe               fA3 = [rTmpPtr2], 48 // A3 or B1

      nop.f              0

      adds               rTmpPtr1 = 64, rTmpPtr3

}

{ .mib

      ldfpd              fA9, fA11 = [rTmpPtr3], 16 // A9, A11 or B10, B11

      // set p11 = 1 if |x| > 1.0

      cmp.gt             p11, p0 = rAbsXBits, rOne

      // branch on special path for |x| > 1.0

(p11) br.cond.spnt       acos_abs_gt_1

}

;;

{ .mfi

      ldfpd              fA17, fA19 = [rTmpPtr2], 16 // A17, A19 or B6, B7

      // initial approximation of 1 / sqrt(1 - x)

      frsqrta.s1         f1mXRcp, p0 = f1mX

      nop.i              0

}

{ .mfi

      ldfpd              fA13, fA15 = [rTmpPtr3] // A13, A15 or B4, B5

      fma.s1             fXCube = fXSqr, f8, f0 // x^3

      nop.i              0

}

;;

{ .mfi

      ldfe               fA5 = [rTmpPtr2], 48 // A5 or B2

      // initial approximation of 1 / sqrt(1 + x)

      frsqrta.s1         f1pXRcp, p0 = f1pX

      nop.i              0

}

{ .mfi

      ldfpd              fA21, fA23 = [rTmpPtr1], 16 // A21, A23 or B3, B8

      fma.s1             fXQuadr = fXSqr, fXSqr, f0 // x^4

      nop.i              0

}

;;

{ .mfi

      ldfe               fA7 = [rTmpPtr1] // A7 or Pi/2

      fma.s1             fRSqr = fR, fR, f0 // R^2

      nop.i              0

}

{ .mfb

      ldfpd              fA25, fA27 = [rTmpPtr2] // A25, A27 or B9, B12

      nop.f              0

(p6)  br.cond.spnt       acos_base_range;

}

;;

{ .mfi

      nop.m              0

(p9)  fma.s1             fH = fHalf, f1mXRcp, f0 // H0 for x > 0

      nop.i              0

}

{ .mfi

      nop.m              0

(p9)  fma.s1             fS = f1mX, f1mXRcp, f0  // S0 for x > 0

      nop.i              0

}

;;

{ .mfi

      nop.m              0

(p8)  fma.s1             fH = fHalf, f1pXRcp, f0 // H0 for x < 0

      nop.i              0

}

{ .mfi

      nop.m              0

(p8)  fma.s1             fS = f1pX, f1pXRcp, f0  // S0 for x > 0

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      fma.s1             fRQuadr = fRSqr, fRSqr, f0 // R^4

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      fma.s1             fB11 = fB11, fR, fB10

      nop.i              0

}

{ .mfi

      nop.m              0

      fma.s1             fB1 = fB1, fR, fB0

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      fma.s1             fB5 = fB5, fR, fB4

      nop.i              0

}

{ .mfi

      nop.m              0

      fma.s1             fB7 = fB7, fR, fB6

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      fma.s1             fB3 = fB3, fR, fB2

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      fnma.s1            fD = fH, fS, fHalf // d0 = 1/2 - H0*S0

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      fma.s1             fR8 = fRQuadr, fRQuadr, f0 // R^4

      nop.i              0

}

{ .mfi

      nop.m              0

      fma.s1             fB9 = fB9, fR, fB8

      nop.i              0

}

;;

{.mfi

      nop.m              0

      fma.s1             fB12 = fB12, fRSqr, fB11

      nop.i              0

}

{.mfi

      nop.m              0

      fma.s1             fB7 = fB7, fRSqr, fB5

      nop.i              0

}

;;

{.mfi

      nop.m              0

      fma.s1             fB3 = fB3, fRSqr, fB1

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      fma.s1             fH = fH, fD, fH // H1 = H0 + H0*d0

      nop.i              0

}

{ .mfi

      nop.m              0

      fma.s1             fS = fS, fD, fS // S1 = S0 + S0*d0

      nop.i              0

}

;;

{.mfi

      nop.m              0

(p9)  fma.s1             fCpi = f1, f0, f0 // Cpi = 0 if x > 0

      nop.i              0

}

{ .mfi

      nop.m              0

(p8)  fma.s1             fCpi = fPiBy2, f1, fPiBy2 // Cpi = Pi if x < 0

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      fma.s1             fB12 = fB12, fRSqr, fB9

      nop.i              0

}

{ .mfi

      nop.m              0

      fma.s1             fB7 = fB7, fRQuadr, fB3

      nop.i              0

}

;;

{.mfi

      nop.m              0

      fnma.s1            fD = fH, fS, fHalf // d1 = 1/2 - H1*S1

      nop.i              0

}

{ .mfi

      nop.m              0

      fnma.s1            fSignedS = fSignX, fS, f0 // -signum(x)*S1

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      fma.s1             fCloseTo1Pol = fB12, fR8, fB7

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      fma.s1             fH = fH, fD, fH // H2 = H1 + H1*d1

      nop.i              0

}

{ .mfi

      nop.m              0

      fma.s1             fS = fS, fD, fS // S2 = S1 + S1*d1

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      // -signum(x)* S2 = -signum(x)*(S1 + S1*d1)

      fma.s1             fSignedS = fSignedS, fD, fSignedS

      nop.i              0

}

;;

{.mfi

      nop.m              0

      fnma.s1            fD = fH, fS, fHalf // d2 = 1/2 - H2*S2

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      // Cpi + signum(x)*PolB*S2

      fnma.s1            fCpi = fSignedS, fCloseTo1Pol, fCpi

      nop.i              0

}

{ .mfi

      nop.m              0

      // signum(x)*PolB * S2

      fnma.s1            fCloseTo1Pol = fSignedS, fCloseTo1Pol, f0

      nop.i              0

}

;;

{ .mfb

      nop.m              0

      // final result for 0.625 <= |x| < 1

      fma.d.s0           f8 = fCloseTo1Pol, fD, fCpi

      // exit here for  0.625 <= |x| < 1

      br.ret.sptk        b0

}

;;

// here if |x| < 0.625

.align 32

acos_base_range:

{ .mfi

      ldfe               fCpi = [rPiBy2Ptr] // Pi/2

      fma.s1             fA33 = fA33, fXSqr, fA31

      nop.i              0

}

{ .mfi

      nop.m              0

      fma.s1             fA15 = fA15, fXSqr, fA13

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      fma.s1             fA29 = fA29, fXSqr, fA27

      nop.i              0

}

{ .mfi

      nop.m              0

      fma.s1             fA25 = fA25, fXSqr, fA23

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      fma.s1             fA21 = fA21, fXSqr, fA19

      nop.i              0

}

{ .mfi

      nop.m              0

      fma.s1             fA9 = fA9, fXSqr, fA7

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      fma.s1             fA5 = fA5, fXSqr, fA3

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      fma.s1             fA35 = fA35, fXQuadr, fA33

      nop.i              0

}

{ .mfi

      nop.m              0

      fma.s1             fA17 = fA17, fXQuadr, fA15

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      fma.s1             fX8 = fXQuadr, fXQuadr, f0 // x^8

      nop.i              0

}

{ .mfi

      nop.m              0

      fma.s1             fA25 = fA25, fXQuadr, fA21

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      fma.s1             fA9 = fA9, fXQuadr, fA5

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      fms.s1             fCpi = fCpi, f1, f8 // Pi/2 - x

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      fma.s1             fA35 = fA35, fXQuadr, fA29

      nop.i              0

}

{ .mfi

      nop.m              0

      fma.s1             fA17 = fA17, fXSqr, fA11

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      fma.s1             fX16 = fX8, fX8, f0 // x^16

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      fma.s1             fA35 = fA35, fX8, fA25

      nop.i              0

}

{ .mfi

      nop.m              0

      fma.s1             fA17 = fA17, fX8, fA9

      nop.i              0

}

;;

{ .mfi

      nop.m              0

      fma.s1             fBaseP = fA35, fX16, fA17

      nop.i              0

}

;;

{ .mfb

      nop.m              0

      // final result for |x| < 0.625

      fnma.d.s0           f8 = fBaseP, fXCube, fCpi

      // exit here for |x| < 0.625 path

      br.ret.sptk        b0

}

;;

// here if |x| = 1

// acos(1) = 0

// acos(-1) = Pi

.align 32

acos_abs_1:

{ .mfi

      ldfe               fPiBy2 = [rPiBy2Ptr] // Pi/2

      nop.f              0

      nop.i              0

}

;;

.pred.rel "mutex", p8, p9

{ .mfi

      nop.m              0

      // result for x = 1.0

(p9)  fma.d.s0           f8 = f1, f0, f0 // 0.0

      nop.i              0

}

{.mfb

      nop.m              0

      // result for x = -1.0

(p8)  fma.d.s0           f8 = fPiBy2, f1, fPiBy2 // Pi

      // exit here for |x| = 1.0

      br.ret.sptk        b0

}

;;

// here if x is a NaN, denormal, or zero

.align 32

acos_special:

{ .mfi

      // point to Pi/2

      adds               rPiBy2Ptr = 272, rTblAddr

      // set p12 = 1 if x is a NaN

      fclass.m           p12, p0 = f8, 0xc3

      nop.i              0

}

{ .mlx

      nop.m              0

      // smallest positive DP normalized number

      movl               rDenoBound = 0x0010000000000000

}

;;

{ .mfi

      ldfe               fPiBy2 = [rPiBy2Ptr] // Pi/2

      // set p13 = 1 if x = 0.0

      fclass.m           p13, p0 = f8, 0x07

      nop.i              0

}

{ .mfi

      nop.m              0

      fnorm.s1           fNormX = f8

      nop.i              0

}

;;

{ .mfb

      // load smallest normal to FP reg

      setf.d             fDenoBound = rDenoBound

      // answer if x is a NaN

(p12) fma.d.s0           f8 = f8,f1,f0

      // exit here if x is a NaN

(p12) br.ret.spnt        b0

}

;;

{ .mfi

      nop.m              0

      // absolute value of normalized x

      fmerge.s           fNormX = f1, fNormX

      nop.i              0

}

;;

{ .mfb

      nop.m              0

      // final result for x = 0

(p13) fma.d.s0           f8 = fPiBy2, f1, f8

      // exit here if x = 0.0

(p13) br.ret.spnt        b0

}

;;

// if we still here then x is denormal or unnormal

{ .mfi

      nop.m              0

      // set p14 = 1 if normalized x is greater than or

      // equal to the smallest denormalized value

      // So, if p14 is set to 1 it means that we deal with

      // unnormal rather than with "true" denormal

      fcmp.ge.s1         p14, p0 = fNormX, fDenoBound

      nop.i              0

}

;;

{ .mfi

      nop.m              0

(p14) fcmp.eq.s0         p6, p0 = f8, f0      // Set D flag if x unnormal

      nop.i              0

}

{ .mfb

      nop.m              0

      // normalize unnormal input

(p14) fnorm.s1           f8 = f8

      // return to the main path

(p14) br.cond.sptk       acos_unnormal_back

}

;;

// if we still here it means that input is "true" denormal

{ .mfb

      nop.m              0

      // final result if x is denormal

      fms.d.s0           f8 = fPiBy2, f1, f8 // Pi/2 - x

      // exit here if x is denormal

      br.ret.sptk        b0

}

;;

// here if |x| > 1.0

// error handler should be called

.align 32

acos_abs_gt_1:

{ .mfi

      alloc              r32 = ar.pfs, 0, 3, 4, 0 // get some registers

      fmerge.s           FR_X = f8,f8

      nop.i              0

}

{ .mfb

      mov                GR_Parameter_TAG = 58 // error code

      frcpa.s0           FR_RESULT, p0 = f0,f0

      // call error handler routine

      br.cond.sptk       __libm_error_region

}

;;

GLOBAL_LIBM_END(acos)

libm_alias_double_other (acos, acos)

LOCAL_LIBM_ENTRY(__libm_error_region)

.prologue

{ .mfi

        add   GR_Parameter_Y=-32,sp             // Parameter 2 value

        nop.f 0

.save   ar.pfs,GR_SAVE_PFS

        mov  GR_SAVE_PFS=ar.pfs                 // Save ar.pfs

}

{ .mfi

.fframe 64

        add sp=-64,sp                           // Create new stack

        nop.f 0

        mov GR_SAVE_GP=gp                       // Save gp

};;

{ .mmi

        stfd [GR_Parameter_Y] = FR_Y,16         // STORE Parameter 2 on stack

        add GR_Parameter_X = 16,sp              // Parameter 1 address

.save   b0, GR_SAVE_B0

        mov GR_SAVE_B0=b0                       // Save b0

};;

.body

{ .mib

        stfd [GR_Parameter_X] = FR_X                  // STORE Parameter 1 on stack

        add   GR_Parameter_RESULT = 0,GR_Parameter_Y  // Parameter 3 address

        nop.b 0

}

{ .mib

        stfd [GR_Parameter_Y] = FR_RESULT             // STORE Parameter 3 on stack

        add   GR_Parameter_Y = -16,GR_Parameter_Y

        br.call.sptk b0=__libm_error_support#         // Call error handling function

};;

{ .mmi

        add   GR_Parameter_RESULT = 48,sp

        nop.m 0

        nop.i 0

};;

{ .mmi

        ldfd  f8 = [GR_Parameter_RESULT]       // Get return result off stack

.restore sp

        add   sp = 64,sp                       // Restore stack pointer

        mov   b0 = GR_SAVE_B0                  // Restore return address

};;

{ .mib

        mov   gp = GR_SAVE_GP                  // Restore gp

        mov   ar.pfs = GR_SAVE_PFS             // Restore ar.pfs

        br.ret.sptk     b0                     // Return

};;

LOCAL_LIBM_END(__libm_error_region)

.type   __libm_error_support#,@function

.global __libm_error_support#