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Diffstat (limited to 'arch/arm/lib/lib1funcs.S')
| -rw-r--r-- | arch/arm/lib/lib1funcs.S | 429 |
1 files changed, 429 insertions, 0 deletions
diff --git a/arch/arm/lib/lib1funcs.S b/arch/arm/lib/lib1funcs.S new file mode 100644 index 00000000000..76968cee172 --- /dev/null +++ b/arch/arm/lib/lib1funcs.S @@ -0,0 +1,429 @@ +/* + * 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. + + * SPDX-License-Identifier: GPL-2.0+ + */ + + +#include <linux/linkage.h> +#include <asm/assembler.h> + +/* + * U-Boot compatibility bit, define empty UNWIND() macro as, since we + * do not support stack unwinding and define CONFIG_AEABI to make all + * of the functions available without diverging from Linux code. + */ +#ifdef __UBOOT__ +#define UNWIND(x...) +#define CONFIG_AEABI +#endif + +.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? + movsne \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 + subsge \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 + + +.pushsection .text.__udivsi3, "ax" +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) +.popsection + +.pushsection .text.__umodsi3, "ax" +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) +.popsection + +.pushsection .text.__divsi3, "ax" +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) +.popsection + +.pushsection .text.__modsi3, "ax" +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) +.popsection + +#ifdef CONFIG_AEABI + +.pushsection .text.__aeabi_uidivmod, "ax" +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) +.popsection + +.pushsection .text.__aeabi_uidivmod, "ax" +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) +.popsection + +#endif + +.pushsection .text.Ldiv0, "ax" +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) +.popsection + +/* Thumb-1 specialities */ +#if defined(CONFIG_SYS_THUMB_BUILD) && !defined(CONFIG_HAS_THUMB2) +.pushsection .text.__gnu_thumb1_case_sqi, "ax" +ENTRY(__gnu_thumb1_case_sqi) + push {r1} + mov r1, lr + lsrs r1, r1, #1 + lsls r1, r1, #1 + ldrsb r1, [r1, r0] + lsls r1, r1, #1 + add lr, lr, r1 + pop {r1} + bx lr +ENDPROC(__gnu_thumb1_case_sqi) +.popsection + +.pushsection .text.__gnu_thumb1_case_uqi, "ax" +ENTRY(__gnu_thumb1_case_uqi) + push {r1} + mov r1, lr + lsrs r1, r1, #1 + lsls r1, r1, #1 + ldrb r1, [r1, r0] + lsls r1, r1, #1 + add lr, lr, r1 + pop {r1} + bx lr +ENDPROC(__gnu_thumb1_case_uqi) +.popsection + +.pushsection .text.__gnu_thumb1_case_shi, "ax" +ENTRY(__gnu_thumb1_case_shi) + push {r0, r1} + mov r1, lr + lsrs r1, r1, #1 + lsls r0, r0, #1 + lsls r1, r1, #1 + ldrsh r1, [r1, r0] + lsls r1, r1, #1 + add lr, lr, r1 + pop {r0, r1} + bx lr +ENDPROC(__gnu_thumb1_case_shi) +.popsection + +.pushsection .text.__gnu_thumb1_case_uhi, "ax" +ENTRY(__gnu_thumb1_case_uhi) + push {r0, r1} + mov r1, lr + lsrs r1, r1, #1 + lsls r0, r0, #1 + lsls r1, r1, #1 + ldrh r1, [r1, r0] + lsls r1, r1, #1 + add lr, lr, r1 + pop {r0, r1} + bx lr +ENDPROC(__gnu_thumb1_case_uhi) +.popsection +#endif |