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      1 // Copyright 2016 The Go Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style
      3 // license that can be found in the LICENSE file.
      4 
      5 #include "textflag.h"
      6 
      7 // Minimax polynomial approximations
      8 DATA tanhrodataL18<>+0(SB)/8, $-1.0
      9 DATA tanhrodataL18<>+8(SB)/8, $-2.0
     10 DATA tanhrodataL18<>+16(SB)/8, $1.0
     11 DATA tanhrodataL18<>+24(SB)/8, $2.0
     12 DATA tanhrodataL18<>+32(SB)/8, $0.20000000000000011868E+01
     13 DATA tanhrodataL18<>+40(SB)/8, $0.13333333333333341256E+01
     14 DATA tanhrodataL18<>+48(SB)/8, $0.26666666663549111502E+00
     15 DATA tanhrodataL18<>+56(SB)/8, $0.66666666658721844678E+00
     16 DATA tanhrodataL18<>+64(SB)/8, $0.88890217768964374821E-01
     17 DATA tanhrodataL18<>+72(SB)/8, $0.25397199429103821138E-01
     18 DATA tanhrodataL18<>+80(SB)/8, $-.346573590279972643E+00
     19 DATA tanhrodataL18<>+88(SB)/8, $20.E0
     20 GLOBL tanhrodataL18<>+0(SB), RODATA, $96
     21 
     22 // Constants
     23 DATA tanhrlog2<>+0(SB)/8, $0x4007154760000000
     24 GLOBL tanhrlog2<>+0(SB), RODATA, $8
     25 DATA tanhxadd<>+0(SB)/8, $0xc2f0000100003ff0
     26 GLOBL tanhxadd<>+0(SB), RODATA, $8
     27 DATA tanhxmone<>+0(SB)/8, $-1.0
     28 GLOBL tanhxmone<>+0(SB), RODATA, $8
     29 DATA tanhxzero<>+0(SB)/8, $0
     30 GLOBL tanhxzero<>+0(SB), RODATA, $8
     31 
     32 // Polynomial coefficients
     33 DATA tanhtab<>+0(SB)/8, $0.000000000000000000E+00
     34 DATA tanhtab<>+8(SB)/8, $-.171540871271399150E-01
     35 DATA tanhtab<>+16(SB)/8, $-.306597931864376363E-01
     36 DATA tanhtab<>+24(SB)/8, $-.410200970469965021E-01
     37 DATA tanhtab<>+32(SB)/8, $-.486343079978231466E-01
     38 DATA tanhtab<>+40(SB)/8, $-.538226193725835820E-01
     39 DATA tanhtab<>+48(SB)/8, $-.568439602538111520E-01
     40 DATA tanhtab<>+56(SB)/8, $-.579091847395528847E-01
     41 DATA tanhtab<>+64(SB)/8, $-.571909584179366341E-01
     42 DATA tanhtab<>+72(SB)/8, $-.548312665987204407E-01
     43 DATA tanhtab<>+80(SB)/8, $-.509471843643441085E-01
     44 DATA tanhtab<>+88(SB)/8, $-.456353588448863359E-01
     45 DATA tanhtab<>+96(SB)/8, $-.389755254243262365E-01
     46 DATA tanhtab<>+104(SB)/8, $-.310332908285244231E-01
     47 DATA tanhtab<>+112(SB)/8, $-.218623539150173528E-01
     48 DATA tanhtab<>+120(SB)/8, $-.115062908917949451E-01
     49 GLOBL tanhtab<>+0(SB), RODATA, $128
     50 
     51 // Tanh returns the hyperbolic tangent of the argument.
     52 //
     53 // Special cases are:
     54 //      Tanh(0) = 0
     55 //      Tanh(Inf) = 1
     56 //      Tanh(NaN) = NaN
     57 // The algorithm used is minimax polynomial approximation using a table of
     58 // polynomial coefficients determined with a Remez exchange algorithm.
     59 
     60 TEXT tanhAsm(SB),NOSPLIT,$0-16
     61 	FMOVD   x+0(FP), F0
     62 	//specail case Tanh(0) = 0
     63 	FMOVD   $(0.0), F1
     64 	FCMPU   F0, F1
     65 	BEQ     tanhIsZero
     66 	MOVD    $tanhrodataL18<>+0(SB), R5
     67 	WORD    $0xB3120000     //ltdbr %f0,%f0
     68 	MOVD    $0x4034000000000000, R1
     69 	BLTU    L15
     70 	FMOVD   F0, F1
     71 L2:
     72 	MOVD    $tanhxadd<>+0(SB), R2
     73 	FMOVD   0(R2), F2
     74 	MOVD    tanhrlog2<>+0(SB), R2
     75 	WORD    $0xB3C10042     //ldgr %f4,%r2
     76 	WFMSDB  V0, V4, V2, V4
     77 	MOVD    $tanhtab<>+0(SB), R3
     78 	WORD    $0xB3CD0024     //lgdr %r2,%f4
     79 	WORD    $0xEC4239BC     //risbg %r4,%r2,57,128+60,3
     80 	BYTE    $0x03
     81 	BYTE    $0x55
     82 	WORD    $0xED105058     //cdb %f1,.L19-.L18(%r5)
     83 	BYTE    $0x00
     84 	BYTE    $0x19
     85 	WORD    $0xEC12000F     //risbgn %r1,%r2,64-64+0,64-64+0+16-1,64-0-16
     86 	BYTE    $0x30
     87 	BYTE    $0x59
     88 	WORD    $0x68543000     //ld %f5,0(%r4,%r3)
     89 	WORD    $0xB3C10061     //ldgr %f6,%r1
     90 	BLT     L3
     91 	MOVD    $tanhxzero<>+0(SB), R1
     92 	FMOVD   0(R1), F2
     93 	WFCHDBS V0, V2, V4
     94 	BEQ     L9
     95 	WFCHDBS V2, V0, V2
     96 	BNE     L1
     97 	MOVD    $tanhxmone<>+0(SB), R1
     98 	FMOVD   0(R1), F0
     99 	FMOVD   F0, ret+8(FP)
    100 	RET
    101 
    102 L3:
    103 	FADD    F4, F2
    104 	FMOVD   tanhrodataL18<>+80(SB), F4
    105 	FMADD   F4, F2, F0, F0
    106 	FMOVD   tanhrodataL18<>+72(SB), F1
    107 	WFMDB   V0, V0, V3
    108 	FMOVD   tanhrodataL18<>+64(SB), F2
    109 	WFMADB  V0, V1, V2, V1
    110 	FMOVD   tanhrodataL18<>+56(SB), F4
    111 	FMOVD   tanhrodataL18<>+48(SB), F2
    112 	WFMADB  V1, V3, V4, V1
    113 	FMOVD   tanhrodataL18<>+40(SB), F4
    114 	WFMADB  V3, V2, V4, V2
    115 	FMOVD   tanhrodataL18<>+32(SB), F4
    116 	WORD    $0xB9270022     //lhr %r2,%r2
    117 	WFMADB  V3, V1, V4, V1
    118 	FMOVD   tanhrodataL18<>+24(SB), F4
    119 	WFMADB  V3, V2, V4, V3
    120 	WFMADB  V0, V5, V0, V2
    121 	WFMADB  V0, V1, V3, V0
    122 	WORD    $0xA7183ECF     //lhi %r1,16079
    123 	WFMADB  V0, V2, V5, V2
    124 	FMUL    F6, F2
    125 	MOVW    R2, R10
    126 	MOVW    R1, R11
    127 	CMPBLE  R10, R11, L16
    128 	FMOVD   F6, F0
    129 	WORD    $0xED005010     //adb %f0,.L28-.L18(%r5)
    130 	BYTE    $0x00
    131 	BYTE    $0x1A
    132 	WORD    $0xA7184330     //lhi %r1,17200
    133 	FADD    F2, F0
    134 	MOVW    R2, R10
    135 	MOVW    R1, R11
    136 	CMPBGT  R10, R11, L17
    137 	WORD    $0xED605010     //sdb %f6,.L28-.L18(%r5)
    138 	BYTE    $0x00
    139 	BYTE    $0x1B
    140 	FADD    F6, F2
    141 	WFDDB   V0, V2, V0
    142 	FMOVD   F0, ret+8(FP)
    143 	RET
    144 
    145 L9:
    146 	FMOVD   tanhrodataL18<>+16(SB), F0
    147 L1:
    148 	FMOVD   F0, ret+8(FP)
    149 	RET
    150 
    151 L15:
    152 	FNEG    F0, F1
    153 	BR      L2
    154 L16:
    155 	FADD    F6, F2
    156 	FMOVD   tanhrodataL18<>+8(SB), F0
    157 	FMADD   F4, F2, F0, F0
    158 	FMOVD   tanhrodataL18<>+0(SB), F4
    159 	FNEG    F0, F0
    160 	WFMADB  V0, V2, V4, V0
    161 	FMOVD   F0, ret+8(FP)
    162 	RET
    163 
    164 L17:
    165 	WFDDB   V0, V4, V0
    166 	FMOVD   tanhrodataL18<>+16(SB), F2
    167 	WFSDB   V0, V2, V0
    168 	FMOVD   F0, ret+8(FP)
    169 	RET
    170 
    171 tanhIsZero:      //return 0
    172 	FMOVD   F0, ret+8(FP)
    173 	RET
    174