diff options
Diffstat (limited to 'ANDROID_3.4.5/arch/arm/lib/div64.S')
| -rw-r--r-- | ANDROID_3.4.5/arch/arm/lib/div64.S | 211 |
1 files changed, 0 insertions, 211 deletions
diff --git a/ANDROID_3.4.5/arch/arm/lib/div64.S b/ANDROID_3.4.5/arch/arm/lib/div64.S deleted file mode 100644 index e55c4842..00000000 --- a/ANDROID_3.4.5/arch/arm/lib/div64.S +++ /dev/null @@ -1,211 +0,0 @@ -/* - * linux/arch/arm/lib/div64.S - * - * Optimized computation of 64-bit dividend / 32-bit divisor - * - * Author: Nicolas Pitre - * Created: Oct 5, 2003 - * Copyright: Monta Vista Software, Inc. - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License version 2 as - * published by the Free Software Foundation. - */ - -#include <linux/linkage.h> -#include <asm/unwind.h> - -#ifdef __ARMEB__ -#define xh r0 -#define xl r1 -#define yh r2 -#define yl r3 -#else -#define xl r0 -#define xh r1 -#define yl r2 -#define yh r3 -#endif - -/* - * __do_div64: perform a division with 64-bit dividend and 32-bit divisor. - * - * Note: Calling convention is totally non standard for optimal code. - * This is meant to be used by do_div() from include/asm/div64.h only. - * - * Input parameters: - * xh-xl = dividend (clobbered) - * r4 = divisor (preserved) - * - * Output values: - * yh-yl = result - * xh = remainder - * - * Clobbered regs: xl, ip - */ - -ENTRY(__do_div64) -UNWIND(.fnstart) - - @ Test for easy paths first. - subs ip, r4, #1 - bls 9f @ divisor is 0 or 1 - tst ip, r4 - beq 8f @ divisor is power of 2 - - @ See if we need to handle upper 32-bit result. - cmp xh, r4 - mov yh, #0 - blo 3f - - @ Align divisor with upper part of dividend. - @ The aligned divisor is stored in yl preserving the original. - @ The bit position is stored in ip. - -#if __LINUX_ARM_ARCH__ >= 5 - - clz yl, r4 - clz ip, xh - sub yl, yl, ip - mov ip, #1 - mov ip, ip, lsl yl - mov yl, r4, lsl yl - -#else - - mov yl, r4 - mov ip, #1 -1: cmp yl, #0x80000000 - cmpcc yl, xh - movcc yl, yl, lsl #1 - movcc ip, ip, lsl #1 - bcc 1b - -#endif - - @ The division loop for needed upper bit positions. - @ Break out early if dividend reaches 0. -2: cmp xh, yl - orrcs yh, yh, ip - subcss xh, xh, yl - movnes ip, ip, lsr #1 - mov yl, yl, lsr #1 - bne 2b - - @ See if we need to handle lower 32-bit result. -3: cmp xh, #0 - mov yl, #0 - cmpeq xl, r4 - movlo xh, xl - movlo pc, lr - - @ The division loop for lower bit positions. - @ Here we shift remainer bits leftwards rather than moving the - @ divisor for comparisons, considering the carry-out bit as well. - mov ip, #0x80000000 -4: movs xl, xl, lsl #1 - adcs xh, xh, xh - beq 6f - cmpcc xh, r4 -5: orrcs yl, yl, ip - subcs xh, xh, r4 - movs ip, ip, lsr #1 - bne 4b - mov pc, lr - - @ The top part of remainder became zero. If carry is set - @ (the 33th bit) this is a false positive so resume the loop. - @ Otherwise, if lower part is also null then we are done. -6: bcs 5b - cmp xl, #0 - moveq pc, lr - - @ We still have remainer bits in the low part. Bring them up. - -#if __LINUX_ARM_ARCH__ >= 5 - - clz xh, xl @ we know xh is zero here so... - add xh, xh, #1 - mov xl, xl, lsl xh - mov ip, ip, lsr xh - -#else - -7: movs xl, xl, lsl #1 - mov ip, ip, lsr #1 - bcc 7b - -#endif - - @ Current remainder is now 1. It is worthless to compare with - @ divisor at this point since divisor can not be smaller than 3 here. - @ If possible, branch for another shift in the division loop. - @ If no bit position left then we are done. - movs ip, ip, lsr #1 - mov xh, #1 - bne 4b - mov pc, lr - -8: @ Division by a power of 2: determine what that divisor order is - @ then simply shift values around - -#if __LINUX_ARM_ARCH__ >= 5 - - clz ip, r4 - rsb ip, ip, #31 - -#else - - mov yl, r4 - cmp r4, #(1 << 16) - mov ip, #0 - movhs yl, yl, lsr #16 - movhs ip, #16 - - cmp yl, #(1 << 8) - movhs yl, yl, lsr #8 - addhs ip, ip, #8 - - cmp yl, #(1 << 4) - movhs yl, yl, lsr #4 - addhs ip, ip, #4 - - cmp yl, #(1 << 2) - addhi ip, ip, #3 - addls ip, ip, yl, lsr #1 - -#endif - - mov yh, xh, lsr ip - mov yl, xl, lsr ip - rsb ip, ip, #32 - ARM( orr yl, yl, xh, lsl ip ) - THUMB( lsl xh, xh, ip ) - THUMB( orr yl, yl, xh ) - mov xh, xl, lsl ip - mov xh, xh, lsr ip - mov pc, lr - - @ eq -> division by 1: obvious enough... -9: moveq yl, xl - moveq yh, xh - moveq xh, #0 - moveq pc, lr -UNWIND(.fnend) - -UNWIND(.fnstart) -UNWIND(.pad #4) -UNWIND(.save {lr}) -Ldiv0_64: - @ Division by 0: - str lr, [sp, #-8]! - bl __div0 - - @ as wrong as it could be... - mov yl, #0 - mov yh, #0 - mov xh, #0 - ldr pc, [sp], #8 - -UNWIND(.fnend) -ENDPROC(__do_div64) |