/* * linux/arch/arm/lib/lib1funcs.S: Optimized ARM division routines * * Author: Nicolas Pitre <nico@cam.org> *   - contributed to gcc-3.4 on Sep 30, 2003 *   - adapted for the Linux kernel on Oct 2, 2003 *//* Copyright 1995, 1996, 1998, 1999, 2000, 2003 Free Software Foundation, Inc.This file is free software; you can redistribute it and/or modify itunder the terms of the GNU General Public License as published by theFree Software Foundation; either version 2, or (at your option) anylater version.In addition to the permissions in the GNU General Public License, theFree Software Foundation gives you unlimited permission to link thecompiled version of this file into combinations with other programs,and to distribute those combinations without any restriction comingfrom the use of this file.  (The General Public License restrictionsdo apply in other respects; for example, they cover modification ofthe file, and distribution when not linked into a combineexecutable.)This file is distributed in the hope that it will be useful, butWITHOUT ANY WARRANTY; without even the implied warranty ofMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNUGeneral Public License for more details.You should have received a copy of the GNU General Public Licensealong with this program; see the file COPYING.  If not, write tothe Free Software Foundation, 59 Temple Place - Suite 330,Boston, MA 02111-1307, USA.  *//*#include <linux/linkage.h>#include <asm/assembler.h>*/#define ALIGN		.align 4,0x90#define __LINUX_ARM_ARCH__  1#define ENTRY(name) \  .globl name; \  ALIGN; \  name:.macro ARM_DIV_BODY dividend, divisor, result, curbit#if __LINUX_ARM_ARCH__ >= 5	clz	\curbit, \divisor	clz	\result, \dividend	sub	\result, \curbit, \result	mov	\curbit, #1	mov	\divisor, \divisor, lsl \result	mov	\curbit, \curbit, lsl \result	mov	\result, #0	#else	@ Initially shift the divisor left 3 bits if possible,	@ set curbit accordingly.  This allows for curbit to be located	@ at the left end of each 4 bit nibbles in the division loop	@ to save one loop in most cases.	tst	\divisor, #0xe0000000	moveq	\divisor, \divisor, lsl #3	moveq	\curbit, #8	movne	\curbit, #1	@ Unless the divisor is very big, shift it up in multiples of	@ four bits, since this is the amount of unwinding in the main	@ division loop.  Continue shifting until the divisor is 	@ larger than the dividend.1:	cmp	\divisor, #0x10000000	cmplo	\divisor, \dividend	movlo	\divisor, \divisor, lsl #4	movlo	\curbit, \curbit, lsl #4	blo	1b	@ For very big divisors, we must shift it a bit at a time, or	@ we will be in danger of overflowing.1:	cmp	\divisor, #0x80000000	cmplo	\divisor, \dividend	movlo	\divisor, \divisor, lsl #1	movlo	\curbit, \curbit, lsl #1	blo	1b	mov	\result, #0#endif	@ Division loop1:	cmp	\dividend, \divisor	subhs	\dividend, \dividend, \divisor	orrhs	\result,   \result,   \curbit	cmp	\dividend, \divisor,  lsr #1	subhs	\dividend, \dividend, \divisor, lsr #1	orrhs	\result,   \result,   \curbit,  lsr #1	cmp	\dividend, \divisor,  lsr #2	subhs	\dividend, \dividend, \divisor, lsr #2	orrhs	\result,   \result,   \curbit,  lsr #2	cmp	\dividend, \divisor,  lsr #3	subhs	\dividend, \dividend, \divisor, lsr #3	orrhs	\result,   \result,   \curbit,  lsr #3	cmp	\dividend, #0			@ Early termination?	movnes	\curbit,   \curbit,  lsr #4	@ No, any more bits to do?	movne	\divisor,  \divisor, lsr #4	bne	1b.endm.macro ARM_DIV2_ORDER divisor, order#if __LINUX_ARM_ARCH__ >= 5	clz	\order, \divisor	rsb	\order, \order, #31#else	cmp	\divisor, #(1 << 16)	movhs	\divisor, \divisor, lsr #16	movhs	\order, #16	movlo	\order, #0	cmp	\divisor, #(1 << 8)	movhs	\divisor, \divisor, lsr #8	addhs	\order, \order, #8	cmp	\divisor, #(1 << 4)	movhs	\divisor, \divisor, lsr #4	addhs	\order, \order, #4	cmp	\divisor, #(1 << 2)	addhi	\order, \order, #3	addls	\order, \order, \divisor, lsr #1#endif.endm.macro ARM_MOD_BODY dividend, divisor, order, spare#if __LINUX_ARM_ARCH__ >= 5	clz	\order, \divisor	clz	\spare, \dividend	sub	\order, \order, \spare	mov	\divisor, \divisor, lsl \order#else	mov	\order, #0	@ Unless the divisor is very big, shift it up in multiples of	@ four bits, since this is the amount of unwinding in the main	@ division loop.  Continue shifting until the divisor is 	@ larger than the dividend.1:	cmp	\divisor, #0x10000000	cmplo	\divisor, \dividend	movlo	\divisor, \divisor, lsl #4	addlo	\order, \order, #4	blo	1b	@ For very big divisors, we must shift it a bit at a time, or	@ we will be in danger of overflowing.1:	cmp	\divisor, #0x80000000	cmplo	\divisor, \dividend	movlo	\divisor, \divisor, lsl #1	addlo	\order, \order, #1	blo	1b#endif	@ Perform all needed substractions to keep only the reminder.	@ Do comparisons in batch of 4 first.	subs	\order, \order, #3		@ yes, 3 is intended here	blt	2f1:	cmp	\dividend, \divisor	subhs	\dividend, \dividend, \divisor	cmp	\dividend, \divisor,  lsr #1	subhs	\dividend, \dividend, \divisor, lsr #1	cmp	\dividend, \divisor,  lsr #2	subhs	\dividend, \dividend, \divisor, lsr #2	cmp	\dividend, \divisor,  lsr #3	subhs	\dividend, \dividend, \divisor, lsr #3	cmp	\dividend, #1	mov	\divisor, \divisor, lsr #4	subges	\order, \order, #4	bge	1b	tst	\order, #3	teqne	\dividend, #0	beq	5f	@ Either 1, 2 or 3 comparison/substractions are left.2:	cmn	\order, #2	blt	4f	beq	3f	cmp	\dividend, \divisor	subhs	\dividend, \dividend, \divisor	mov	\divisor,  \divisor,  lsr #13:	cmp	\dividend, \divisor	subhs	\dividend, \dividend, \divisor	mov	\divisor,  \divisor,  lsr #14:	cmp	\dividend, \divisor	subhs	\dividend, \dividend, \divisor5:.endmENTRY(__udivsi3)	subs	r2, r1, #1	moveq	pc, lr	bcc	Ldiv0	cmp	r0, r1	bls	11f	tst	r1, r2	beq	12f	ARM_DIV_BODY r0, r1, r2, r3	mov	r0, r2	mov	pc, lr11:	moveq	r0, #1	movne	r0, #0	mov	pc, lr12:	ARM_DIV2_ORDER r1, r2	mov	r0, r0, lsr r2	mov	pc, lrENTRY(__umodsi3)	subs	r2, r1, #1			@ compare divisor with 1	bcc	Ldiv0	cmpne	r0, r1				@ compare dividend with divisor	moveq   r0, #0	tsthi	r1, r2				@ see if divisor is power of 2	andeq	r0, r0, r2	movls	pc, lr	ARM_MOD_BODY r0, r1, r2, r3	mov	pc, lrENTRY(__divsi3)	cmp	r1, #0	eor	ip, r0, r1			@ save the sign of the result.	beq	Ldiv0	rsbmi	r1, r1, #0			@ loops below use unsigned.	subs	r2, r1, #1			@ division by 1 or -1 ?	beq	10f	movs	r3, r0	rsbmi	r3, r0, #0			@ positive dividend value	cmp	r3, r1	bls	11f	tst	r1, r2				@ divisor is power of 2 ?	beq	12f	ARM_DIV_BODY r3, r1, r0, r2	cmp	ip, #0	rsbmi	r0, r0, #0	mov	pc, lr10:	teq	ip, r0				@ same sign ?	rsbmi	r0, r0, #0	mov	pc, lr11:	movlo	r0, #0	moveq	r0, ip, asr #31	orreq	r0, r0, #1	mov	pc, lr12:	ARM_DIV2_ORDER r1, r2	cmp	ip, #0	mov	r0, r3, lsr r2	rsbmi	r0, r0, #0	mov	pc, lrENTRY(__modsi3)	cmp	r1, #0	beq	Ldiv0	rsbmi	r1, r1, #0			@ loops below use unsigned.	movs	ip, r0				@ preserve sign of dividend	rsbmi	r0, r0, #0			@ if negative make positive	subs	r2, r1, #1			@ compare divisor with 1	cmpne	r0, r1				@ compare dividend with divisor	moveq	r0, #0	tsthi	r1, r2				@ see if divisor is power of 2	andeq	r0, r0, r2	bls	10f	ARM_MOD_BODY r0, r1, r2, r310:	cmp	ip, #0	rsbmi	r0, r0, #0	mov	pc, lrLdiv0:	str	lr, [sp, #-4]!/*	bl	__div0	*/	mov	r0, #0			@ About as wrong as it could be.	ldr	pc, [sp], #4