mirror of
https://github.com/make-42/xyosc
synced 2025-01-18 18:57:10 +01:00
115 lines
2.9 KiB
ArmAsm
115 lines
2.9 KiB
ArmAsm
//go:build !tinygo && !noasm
|
|
// Copyright 2014 Xuanyi Chew. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
//
|
|
// The original code is lifted from the Go standard library which is governed by
|
|
// a BSD-style licence which can be found here: https://golang.org/LICENSE
|
|
|
|
#include "textflag.h"
|
|
|
|
// The method is based on a paper by Naoki Shibata: "Efficient evaluation
|
|
// methods of elementary functions suitable for SIMD computation", Proc.
|
|
// of International Supercomputing Conference 2010 (ISC'10), pp. 25 -- 32
|
|
// (May 2010). The paper is available at
|
|
// http://www.springerlink.com/content/340228x165742104/
|
|
//
|
|
// The original code and the constants below are from the author's
|
|
// implementation available at http://freshmeat.net/projects/sleef.
|
|
// The README file says, "The software is in public domain.
|
|
// You can use the software without any obligation."
|
|
//
|
|
// This code is a simplified version of the original.
|
|
// The magic numbers for the float32 are lifted from the same project
|
|
|
|
|
|
#define LN2 0.693147182464599609375 // log_e(2)
|
|
#define LOG2E 1.44269502162933349609375 // 1/LN2
|
|
#define LN2U 0.693145751953125 // upper half LN2
|
|
#define LN2L 1.428606765330187045e-06 // lower half LN2
|
|
#define T0 1.0
|
|
#define T1 0.5
|
|
#define T2 0.166665524244308471679688
|
|
#define T3 0.0416710823774337768554688
|
|
#define T4 0.00836596917361021041870117
|
|
#define PosInf 0x7F800000
|
|
#define NegInf 0xFF800000
|
|
|
|
// func archExp(x float32) float32
|
|
TEXT ·archExp(SB),NOSPLIT,$0
|
|
// test bits for not-finite
|
|
MOVL x+0(FP), BX
|
|
MOVQ $~(1<<31), AX // sign bit mask
|
|
MOVL BX, DX
|
|
ANDL AX, DX
|
|
MOVL $PosInf, AX
|
|
CMPL AX, DX
|
|
JLE notFinite
|
|
MOVL BX, X0
|
|
MOVSS $LOG2E, X1
|
|
MULSS X0, X1
|
|
CVTSS2SL X1, BX // BX = exponent
|
|
CVTSL2SS BX, X1
|
|
MOVSS $LN2U, X2
|
|
MULSS X1, X2
|
|
SUBSS X2, X0
|
|
MOVSS $LN2L, X2
|
|
MULSS X1, X2
|
|
SUBSS X2, X0
|
|
// reduce argument
|
|
MULSS $0.0625, X0
|
|
// Taylor series evaluation
|
|
ADDSS $T4, X1
|
|
MULSS X0, X1
|
|
ADDSS $T3, X1
|
|
MULSS X0, X1
|
|
ADDSS $T2, X1
|
|
MULSS X0, X1
|
|
ADDSS $T1, X1
|
|
MULSS X0, X1
|
|
ADDSS $T0, X1
|
|
MULSS X1, X0
|
|
MOVSS $2.0, X1
|
|
ADDSS X0, X1
|
|
MULSS X1, X0
|
|
MOVSS $2.0, X1
|
|
ADDSS X0, X1
|
|
MULSS X1, X0
|
|
MOVSS $2.0, X1
|
|
ADDSS X0, X1
|
|
MULSS X1, X0
|
|
MOVSS $2.0, X1
|
|
ADDSS X0, X1
|
|
MULSS X1, X0
|
|
ADDSS $1.0, X0
|
|
// return fr * 2**exponent
|
|
MOVL $0x7F, AX // bias
|
|
ADDL AX, BX
|
|
JLE underflow
|
|
CMPL BX, $0xFF
|
|
JGE overflow
|
|
MOVL $23, CX
|
|
SHLQ CX, BX
|
|
MOVL BX, X1
|
|
MULSS X1, X0
|
|
MOVSS X0, ret+8(FP)
|
|
RET
|
|
notFinite:
|
|
// test bits for -Inf
|
|
MOVL $NegInf, AX
|
|
CMPQ AX, BX
|
|
JNE notNegInf
|
|
// -Inf, return 0
|
|
underflow: // return 0
|
|
MOVL $0, AX
|
|
MOVL AX, ret+8(FP)
|
|
RET
|
|
overflow: // return +Inf
|
|
MOVL $PosInf, BX
|
|
notNegInf: // NaN or +Inf, return x
|
|
MOVL BX, ret+8(FP)
|
|
RET
|
|
|
|
TEXT ·archExp2(SB),NOSPLIT,$0
|
|
JMP ·exp2(SB)
|