| /* |
| * linux/arch/arm/lib/lib1funcs.S: Optimized ARM division routines |
| * |
| * Author: Nicolas Pitre <nico@fluxnic.net> |
| * - 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 it |
| under the terms of the GNU General Public License as published by the |
| Free Software Foundation; either version 2, or (at your option) any |
| later version. |
| |
| In addition to the permissions in the GNU General Public License, the |
| Free Software Foundation gives you unlimited permission to link the |
| compiled version of this file into combinations with other programs, |
| and to distribute those combinations without any restriction coming |
| from the use of this file. (The General Public License restrictions |
| do apply in other respects; for example, they cover modification of |
| the file, and distribution when not linked into a combine |
| executable.) |
| |
| This file is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program; see the file COPYING. If not, write to |
| the Free Software Foundation, 59 Temple Place - Suite 330, |
| Boston, MA 02111-1307, USA. */ |
| |
| |
| #include <linux/linkage.h> |
| #include <asm/assembler.h> |
| #include <asm/unwind.h> |
| |
| .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 loop |
| 1: 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 subtractions to keep only the reminder. |
| @ Do comparisons in batch of 4 first. |
| subs \order, \order, #3 @ yes, 3 is intended here |
| blt 2f |
| |
| 1: 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/subtractions are left. |
| 2: cmn \order, #2 |
| blt 4f |
| beq 3f |
| cmp \dividend, \divisor |
| subhs \dividend, \dividend, \divisor |
| mov \divisor, \divisor, lsr #1 |
| 3: cmp \dividend, \divisor |
| subhs \dividend, \dividend, \divisor |
| mov \divisor, \divisor, lsr #1 |
| 4: cmp \dividend, \divisor |
| subhs \dividend, \dividend, \divisor |
| 5: |
| .endm |
| |
| |
| #ifdef CONFIG_ARM_PATCH_IDIV |
| .align 3 |
| #endif |
| |
| ENTRY(__udivsi3) |
| ENTRY(__aeabi_uidiv) |
| UNWIND(.fnstart) |
| |
| subs r2, r1, #1 |
| reteq lr |
| bcc Ldiv0 |
| cmp r0, r1 |
| bls 11f |
| tst r1, r2 |
| beq 12f |
| |
| ARM_DIV_BODY r0, r1, r2, r3 |
| |
| mov r0, r2 |
| ret lr |
| |
| 11: moveq r0, #1 |
| movne r0, #0 |
| ret lr |
| |
| 12: ARM_DIV2_ORDER r1, r2 |
| |
| mov r0, r0, lsr r2 |
| ret lr |
| |
| UNWIND(.fnend) |
| ENDPROC(__udivsi3) |
| ENDPROC(__aeabi_uidiv) |
| |
| ENTRY(__umodsi3) |
| UNWIND(.fnstart) |
| |
| 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 |
| retls lr |
| |
| ARM_MOD_BODY r0, r1, r2, r3 |
| |
| ret lr |
| |
| UNWIND(.fnend) |
| ENDPROC(__umodsi3) |
| |
| #ifdef CONFIG_ARM_PATCH_IDIV |
| .align 3 |
| #endif |
| |
| ENTRY(__divsi3) |
| ENTRY(__aeabi_idiv) |
| UNWIND(.fnstart) |
| |
| 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 |
| ret lr |
| |
| 10: teq ip, r0 @ same sign ? |
| rsbmi r0, r0, #0 |
| ret lr |
| |
| 11: movlo r0, #0 |
| moveq r0, ip, asr #31 |
| orreq r0, r0, #1 |
| ret lr |
| |
| 12: ARM_DIV2_ORDER r1, r2 |
| |
| cmp ip, #0 |
| mov r0, r3, lsr r2 |
| rsbmi r0, r0, #0 |
| ret lr |
| |
| UNWIND(.fnend) |
| ENDPROC(__divsi3) |
| ENDPROC(__aeabi_idiv) |
| |
| ENTRY(__modsi3) |
| UNWIND(.fnstart) |
| |
| 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, r3 |
| |
| 10: cmp ip, #0 |
| rsbmi r0, r0, #0 |
| ret lr |
| |
| UNWIND(.fnend) |
| ENDPROC(__modsi3) |
| |
| #ifdef CONFIG_AEABI |
| |
| ENTRY(__aeabi_uidivmod) |
| UNWIND(.fnstart) |
| UNWIND(.save {r0, r1, ip, lr} ) |
| |
| stmfd sp!, {r0, r1, ip, lr} |
| bl __aeabi_uidiv |
| ldmfd sp!, {r1, r2, ip, lr} |
| mul r3, r0, r2 |
| sub r1, r1, r3 |
| ret lr |
| |
| UNWIND(.fnend) |
| ENDPROC(__aeabi_uidivmod) |
| |
| ENTRY(__aeabi_idivmod) |
| UNWIND(.fnstart) |
| UNWIND(.save {r0, r1, ip, lr} ) |
| stmfd sp!, {r0, r1, ip, lr} |
| bl __aeabi_idiv |
| ldmfd sp!, {r1, r2, ip, lr} |
| mul r3, r0, r2 |
| sub r1, r1, r3 |
| ret lr |
| |
| UNWIND(.fnend) |
| ENDPROC(__aeabi_idivmod) |
| |
| #endif |
| |
| Ldiv0: |
| UNWIND(.fnstart) |
| UNWIND(.pad #4) |
| UNWIND(.save {lr}) |
| str lr, [sp, #-8]! |
| bl __div0 |
| mov r0, #0 @ About as wrong as it could be. |
| ldr pc, [sp], #8 |
| UNWIND(.fnend) |
| ENDPROC(Ldiv0) |