OpenBLAS/kernel/arm64/iamax.S

/*******************************************************************************
Copyright (c) 2015, The OpenBLAS Project
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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ARE DISCLAIMED. IN NO EVENT SHALL THE OPENBLAS PROJECT OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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*******************************************************************************/

#define ASSEMBLER
#include "common.h"

#define	N	x0	/* vector length */
#define	X	x1	/* X vector address */
#define	INC_X	x2	/* X stride */
#define INDEX	x3	/* index of max/min value */
#define Z	x4	/* vector index */
#define I	x5	/* loop variable */

/*******************************************************************************
* Macro definitions
*******************************************************************************/

#if defined(USE_MIN)
#define COND	le
#else
#define COND	ge
#endif

#if !defined(DOUBLE)
#define MAXF	s0
#define TMPF	s1
#define TMPVF	{v1.s}[0]
#define SZ	4
#else
#define MAXF	d0
#define TMPF	d1
#define TMPVF	{v1.d}[0]
#define SZ	8
#endif

/******************************************************************************/

.macro INIT_S
#if !defined(DOUBLE)
	lsl	INC_X, INC_X, #2
	ld1	{v0.s}[0], [X], INC_X
#else
	lsl	INC_X, INC_X, #3
	ld1	{v0.d}[0], [X], INC_X
#endif
	mov	Z, #1
	mov	INDEX, Z
	fabs	MAXF, MAXF
.endm

.macro KERNEL_S1
	ld1	TMPVF, [X], INC_X
	add	Z, Z, #1
	fabs	TMPF, TMPF
	fcmp	MAXF, TMPF
	fcsel	MAXF, MAXF, TMPF, COND
	csel	INDEX, INDEX, Z, COND
.endm

/*******************************************************************************
* End of macro definitions
*******************************************************************************/

	PROLOGUE

	cmp	N, xzr
	ble	iamax_kernel_zero
	cmp	INC_X, xzr
	ble	iamax_kernel_zero

	INIT_S

	subs	N, N, #1
	ble	iamax_kernel_L999

	asr	I, N, #2
	cmp	I, xzr
	ble	iamax_kernel_S1

iamax_kernel_S4:

	KERNEL_S1
	KERNEL_S1
	KERNEL_S1
	KERNEL_S1

	subs	I, I, #1
	bne	iamax_kernel_S4

iamax_kernel_S1:

	ands	I, N, #3
	ble	iamax_kernel_L999

iamax_kernel_S10:

	KERNEL_S1
	subs	I, I, #1
	bne	iamax_kernel_S10

iamax_kernel_L999:

	mov	x0, INDEX
	ret

iamax_kernel_zero:

	mov	x0, xzr
	ret

	EPILOGUE