diff options
Diffstat (limited to 'src/pkg/math/exp_amd64.s')
| -rw-r--r-- | src/pkg/math/exp_amd64.s | 92 |
1 files changed, 50 insertions, 42 deletions
diff --git a/src/pkg/math/exp_amd64.s b/src/pkg/math/exp_amd64.s index 844b5c923..74c9c876a 100644 --- a/src/pkg/math/exp_amd64.s +++ b/src/pkg/math/exp_amd64.s @@ -19,20 +19,32 @@ #define LOG2E 1.4426950408889634073599246810018920 // 1/LN2 #define LN2U 0.69314718055966295651160180568695068359375 // upper half LN2 #define LN2L 0.28235290563031577122588448175013436025525412068e-12 // lower half LN2 +#define T0 1.0 +#define T1 0.5 +#define T2 1.6666666666666666667e-1 +#define T3 4.1666666666666666667e-2 +#define T4 8.3333333333333333333e-3 +#define T5 1.3888888888888888889e-3 +#define T6 1.9841269841269841270e-4 +#define T7 2.4801587301587301587e-5 +#define PosInf 0x7FF0000000000000 +#define NegInf 0xFFF0000000000000 // func Exp(x float64) float64 TEXT ·Exp(SB),7,$0 // test bits for not-finite - MOVQ x+0(FP), AX - MOVQ $0x7ff0000000000000, BX - ANDQ BX, AX - CMPQ BX, AX - JEQ not_finite - MOVSD x+0(FP), X0 + MOVQ x+0(FP), BX + MOVQ $~(1<<63), AX // sign bit mask + MOVQ BX, DX + ANDQ AX, DX + MOVQ $PosInf, AX + CMPQ AX, DX + JLE notFinite + MOVQ BX, X0 MOVSD $LOG2E, X1 MULSD X0, X1 - CVTTSD2SQ X1, BX // BX = exponent - CVTSQ2SD BX, X1 + CVTSD2SL X1, BX // BX = exponent + CVTSL2SD BX, X1 MOVSD $LN2U, X2 MULSD X1, X2 SUBSD X2, X0 @@ -40,31 +52,23 @@ TEXT ·Exp(SB),7,$0 MULSD X1, X2 SUBSD X2, X0 // reduce argument - MOVSD $0.0625, X1 - MULSD X1, X0 + MULSD $0.0625, X0 // Taylor series evaluation - MOVSD $2.4801587301587301587e-5, X1 + MOVSD $T7, X1 MULSD X0, X1 - MOVSD $1.9841269841269841270e-4, X2 - ADDSD X2, X1 + ADDSD $T6, X1 MULSD X0, X1 - MOVSD $1.3888888888888888889e-3, X2 - ADDSD X2, X1 + ADDSD $T5, X1 MULSD X0, X1 - MOVSD $8.3333333333333333333e-3, X2 - ADDSD X2, X1 + ADDSD $T4, X1 MULSD X0, X1 - MOVSD $4.1666666666666666667e-2, X2 - ADDSD X2, X1 + ADDSD $T3, X1 MULSD X0, X1 - MOVSD $1.6666666666666666667e-1, X2 - ADDSD X2, X1 + ADDSD $T2, X1 MULSD X0, X1 - MOVSD $0.5, X2 - ADDSD X2, X1 + ADDSD $T1, X1 MULSD X0, X1 - MOVSD $1.0, X2 - ADDSD X2, X1 + ADDSD $T0, X1 MULSD X1, X0 MOVSD $2.0, X1 ADDSD X0, X1 @@ -78,27 +82,31 @@ TEXT ·Exp(SB),7,$0 MOVSD $2.0, X1 ADDSD X0, X1 MULSD X1, X0 - MOVSD $1.0, X1 - ADDSD X1, X0 - // return ldexp(fr, exp) - MOVQ $0x3ff, AX // bias + 1 - ADDQ AX, BX + ADDSD $1.0, X0 + // return fr * 2**exponent + MOVL $0x3FF, AX // bias + ADDL AX, BX + JLE underflow + CMPL BX, $0x7FF + JGE overflow + MOVL $52, CX + SHLQ CX, BX MOVQ BX, X1 - MOVQ $52, AX // shift - MOVQ AX, X2 - PSLLQ X2, X1 MULSD X1, X0 MOVSD X0, r+8(FP) RET -not_finite: -// test bits for -Inf - MOVQ x+0(FP), AX - MOVQ $0xfff0000000000000, BX - CMPQ BX, AX - JNE not_neginf - XORQ AX, AX +notFinite: + // test bits for -Inf + MOVQ $NegInf, AX + CMPQ AX, BX + JNE notNegInf + // -Inf, return 0 +underflow: // return 0 + MOVQ $0, AX MOVQ AX, r+8(FP) RET -not_neginf: - MOVQ AX, r+8(FP) +overflow: // return +Inf + MOVQ $PosInf, BX +notNegInf: // NaN or +Inf, return x + MOVQ BX, r+8(FP) RET |