1 files changed, 128 insertions, 0 deletions
diff --git a/src/math/atan_s390x.s b/src/math/atan_s390x.s
new file mode 100644
index 0000000..3a7e59b
--- /dev/null
+++ b/src/math/atan_s390x.s
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+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "textflag.h"
+
+// Minimax polynomial coefficients and other constants
+DATA ·atanrodataL8<> + 0(SB)/8, $0.199999999999554423E+00
+DATA ·atanrodataL8<> + 8(SB)/8, $0.111111110136634272E+00
+DATA ·atanrodataL8<> + 16(SB)/8, $-.142857142828026806E+00
+DATA ·atanrodataL8<> + 24(SB)/8, $-.333333333333330928E+00
+DATA ·atanrodataL8<> + 32(SB)/8, $0.769228118888682505E-01
+DATA ·atanrodataL8<> + 40(SB)/8, $0.588059263575587687E-01
+DATA ·atanrodataL8<> + 48(SB)/8, $-.666641501287528609E-01
+DATA ·atanrodataL8<> + 56(SB)/8, $-.909090711945939878E-01
+DATA ·atanrodataL8<> + 64(SB)/8, $0.472329433805024762E-01
+DATA ·atanrodataL8<> + 72(SB)/8, $0.366935664549587481E-01
+DATA ·atanrodataL8<> + 80(SB)/8, $-.422172007412067035E-01
+DATA ·atanrodataL8<> + 88(SB)/8, $-.299856214685512712E-01
+DATA ·atanrodataL8<> + 96(SB)/8, $0.220852012160300086E-01
+DATA ·atanrodataL8<> + 104(SB)/8, $0.726338160757602439E-02
+DATA ·atanrodataL8<> + 112(SB)/8, $0.843488472994227321E-03
+DATA ·atanrodataL8<> + 120(SB)/8, $0.134893651284712515E-04
+DATA ·atanrodataL8<> + 128(SB)/8, $-.525380587584426406E-01
+DATA ·atanrodataL8<> + 136(SB)/8, $-.139950258898989925E-01
+DATA ·atanrodataL8<> + 144(SB)/8, $-.291935324869629616E-02
+DATA ·atanrodataL8<> + 152(SB)/8, $-.154797890856877418E-03
+GLOBL ·atanrodataL8<> + 0(SB), RODATA, $160
+
+DATA ·atanxpi2h<> + 0(SB)/8, $0x3ff330e4e4fa7b1b
+DATA ·atanxpi2h<> + 8(SB)/8, $0xbff330e4e4fa7b1b
+DATA ·atanxpi2h<> + 16(SB)/8, $0x400330e4e4fa7b1b
+DATA ·atanxpi2h<> + 24(SB)/4, $0xc00330e4e4fa7b1b
+GLOBL ·atanxpi2h<> + 0(SB), RODATA, $32
+DATA ·atanxpim<> + 0(SB)/8, $0x3ff4f42b00000000
+GLOBL ·atanxpim<> + 0(SB), RODATA, $8
+DATA ·atanxmone<> + 0(SB)/8, $-1.0
+GLOBL ·atanxmone<> + 0(SB), RODATA, $8
+
+// Atan returns the arctangent, in radians, of the argument.
+//
+// Special cases are:
+//      Atan(±0) = ±0
+//      Atan(±Inf) = ±Pi/2Pi
+// The algorithm used is minimax polynomial approximation
+// with coefficients determined with a Remez exchange algorithm.
+
+TEXT	·atanAsm(SB), NOSPLIT, $0-16
+	FMOVD	x+0(FP), F0
+	//special case Atan(±0) = ±0
+	FMOVD   $(0.0), F1
+	FCMPU   F0, F1
+	BEQ     atanIsZero
+
+	MOVD	$·atanrodataL8<>+0(SB), R5
+	MOVH	$0x3FE0, R3
+	LGDR	F0, R1
+	RISBGNZ	$32, $63, $32, R1, R1
+	RLL	$16, R1, R2
+	ANDW	$0x7FF0, R2
+	MOVW	R2, R6
+	MOVW	R3, R7
+	CMPUBLE	R6, R7, L6
+	MOVD	$·atanxmone<>+0(SB), R3
+	FMOVD	0(R3), F2
+	WFDDB	V0, V2, V0
+	RISBGZ	$63, $63, $33, R1, R1
+	MOVD	$·atanxpi2h<>+0(SB), R3
+	MOVWZ	R1, R1
+	SLD	$3, R1, R1
+	WORD	$0x68813000	//ld	%f8,0(%r1,%r3)
+L6:
+	WFMDB	V0, V0, V2
+	FMOVD	152(R5), F6
+	FMOVD	144(R5), F1
+	FMOVD	136(R5), F7
+	VLEG	$0, 128(R5), V16
+	FMOVD	120(R5), F4
+	FMOVD	112(R5), F5
+	WFMADB	V2, V4, V6, V4
+	WFMADB	V2, V5, V1, V5
+	WFMDB	V2, V2, V6
+	FMOVD	104(R5), F3
+	FMOVD	96(R5), F1
+	WFMADB	V2, V3, V7, V3
+	MOVH	$0x3FE0, R1
+	FMOVD	88(R5), F7
+	WFMADB	V2, V1, V7, V1
+	FMOVD	80(R5), F7
+	WFMADB	V6, V3, V1, V3
+	WFMADB	V6, V4, V5, V4
+	WFMDB	V6, V6, V1
+	FMOVD	72(R5), F5
+	WFMADB	V2, V5, V7, V5
+	FMOVD	64(R5), F7
+	WFMADB	V2, V7, V16, V7
+	VLEG	$0, 56(R5), V16
+	WFMADB	V6, V5, V7, V5
+	WFMADB	V1, V4, V3, V4
+	FMOVD	48(R5), F7
+	FMOVD	40(R5), F3
+	WFMADB	V2, V3, V7, V3
+	FMOVD	32(R5), F7
+	WFMADB	V2, V7, V16, V7
+	VLEG	$0, 24(R5), V16
+	WFMADB	V1, V4, V5, V4
+	FMOVD	16(R5), F5
+	WFMADB	V6, V3, V7, V3
+	FMOVD	8(R5), F7
+	WFMADB	V2, V7, V5, V7
+	FMOVD	0(R5), F5
+	WFMADB	V2, V5, V16, V5
+	WFMADB	V1, V4, V3, V4
+	WFMADB	V6, V7, V5, V6
+	FMUL	F0, F2
+	FMADD	F4, F1, F6
+	FMADD	F6, F2, F0
+	MOVW	R2, R6
+	MOVW	R1, R7
+	CMPUBLE	R6, R7, L1
+	MOVD	$·atanxpim<>+0(SB), R1
+	WORD	$0xED801000	//madb	%f0,%f8,0(%r1)
+	BYTE	$0x00
+	BYTE	$0x1E
+L1:
+atanIsZero:
+	FMOVD	F0, ret+8(FP)
+	RET