/* ffsALib.s - ARM find first set assembly routines *//* Copyright 1996-1997 Wind River Systems, Inc. *//*modification history--------------------01e,17oct01,t_m  convert to FUNC_LABEL:01d,11oct01,jb  Enabling removal of pre-pended underscores for new compilers                 (Diab/Gnu elf)01c,27oct97,kkk  took out "***EOF***" line from end of file.01b,27may97,jpd  Amalgamated into VxWorks.01a,04jul96,ams  Written.*//*DESCRIPTIONThis library implements ffsMsb() and ffsLsb() which returns the most and leastsignificant bit set respectively.*/#define _ASMLANGUAGE#include "vxWorks.h"#include "asm.h"	.data	.globl	FUNC(copyright_wind_river)	.long	FUNC(copyright_wind_river)#if (defined(PORTABLE))#define ffsALib_PORTABLE#endif#ifndef ffsALib_PORTABLE	/* Exports */	.global	FUNC(ffsMsb)	.global	FUNC(ffsLsb)	/* externals */	.extern	FUNC(ffsMsbTbl)	.extern	FUNC(ffsLsbTbl)	.text	.balign	4/* PC-relative-addressable pointers - LDR Rn,=sym was (is?) broken */L$_MsbTblAddr:	.long	FUNC(ffsMsbTbl)L$_LsbTblAddr:	.long	FUNC(ffsLsbTbl)/********************************************************************************* ffsMsb - find first set bit (searching from the most significant bit)** This routine finds the first bit set in the argument passed it and* returns the index of that bit.  Bits are numbered starting* at 1 from the least significant bit.  A return value of zero indicates that* the value passed is zero.** RETURNS: most significant bit set** NOMANUAL** void ffsMsb*	(*	int i	/@ argument to find first set bit in @/*	)**/FUNC_LABEL(ffsMsb)#ifdef STACK_FRAMES	mov	ip, sp	stmdb	sp!, {fp, ip, lr, pc}	sub	fp, ip, #4#endif /* STACK_FRAMES */	/*  Quick test for 0 */	cmp	r0, #0#ifdef STACK_FRAMES	ldmeqdb	fp, {fp, sp, pc}#else /* !STACK_FRAMES */	moveq	pc, lr#endif /* STACK_FRAMES */	/* Get reference to Msb table */	ldr	ip, L$_MsbTblAddr	/* Test which half */	movs	r1, r0, lsr #16		/* Get upper 16 bits */	beq	0f			/* If 0 then in lower */	/* UPPER HALF */	movs	r0, r1, lsr #8		/* Get upper 8 bits */	ldrneb	r0, [r0, ip]		/* If non-zero, byte 3 of initial r0 */	addne	r0, r0, #25	ldreqb	r0, [r1, ip]		/* If zero, byte 2 of initial r0 */	addeq	r0, r0, #17	/* Done */#ifdef STACK_FRAMES	ldmdb	fp, {fp, sp, pc}#else /* !STACK_FRAMES */	mov	pc, lr#endif /* STACK_FRAMES */	/* LOWER HALF */0:	movs	r1, r0, lsr #8		/* Get upper 8 bits */	ldrneb	r0, [r1, ip]		/* If non-zero, byte 1 of initial r0 */	addne	r0, r0, #9	ldreqb	r0, [r0, ip]		/* If zero, byte 0 of initial r0 */	addeq	r0, r0, #1	/* Done */#ifdef STACK_FRAMES	ldmdb	fp, {fp, sp, pc}#else /* !STACK_FRAMES */	mov	pc, lr#endif /* STACK_FRAMES *//********************************************************************************* ffsLsb - find first set bit (searching from the least significant bit)** This routine finds the first bit set in the argument passed it and* returns the index of that bit.  Bits are numbered starting* at 1 from the least significant bit.  A return value of zero indicates that* the value passed is zero.** RETURNS: least significant bit set** NOMANUAL** void ffsLsb*	(*	int i	/@ argument to find first set bit in @/*	)**/FUNC_LABEL(ffsLsb)#ifdef STACK_FRAMES	mov	ip, sp	stmdb	sp!, {fp, ip, lr, pc}	sub	fp, ip, #4#endif /* STACK_FRAMES */	/* Quick test for 0 */	cmp	r0, #0#ifdef STACK_FRAMES	ldmeqdb	fp, {fp, sp, pc}#else /* !STACK_FRAMES */	moveq	pc, lr#endif /* STACK_FRAMES */	/* Get reference to Msb table */	ldr	ip, L$_LsbTblAddr	/* Test which half */	movs	r1, r0, lsl #16		/* Get & check lower 16 bits */	beq	0f			/* If 0, then in upper */	/* LOWER HALF */	ands	r0, r0, #255		/* Check lower 8 bits (byte 0 in r0) */	ldrneb	r0, [r0, ip]		/* If non-zero, byte 0 of original r0 */	addne	r0, r0, #1		moveq	r0, r1, lsr #24		/* If zero, byte 1 of original r0 */	ldreqb	r0, [r0, ip]	addeq	r0, r0, #9	/* Done */#ifdef STACK_FRAMES	ldmdb	fp, {fp, sp, pc}#else /* !STACK_FRAMES */	mov	pc, lr#endif /* STACK_FRAMES */	/* UPPER HALF */0:	mov	r0, r0, lsr #16		/* Get upper 16 bits */	ands	r1, r0, #255		/* Check lower 8 bits (byte 2 in r0) */	ldrneb	r0, [r1, ip]		/* If non-zero, byte 2 of original r0 */	addne	r0, r0, #17		moveq	r0, r0, lsr #8		/* If zero, byte 3 of original r0 */	ldreqb	r0, [r0, ip]	addeq	r0, r0, #25	/* Done */#ifdef STACK_FRAMES	ldmdb	fp, {fp, sp, pc}#else /* !STACK_FRAMES */	mov	pc, lr#endif /* STACK_FRAMES */#endif /* ! ffsALib_PORTABLE */