diff options
Diffstat (limited to 'third_party/libaeabi-cortexm0/core/cortex-m/uldivmod.S')
| -rw-r--r-- | third_party/libaeabi-cortexm0/core/cortex-m/uldivmod.S | 180 |
1 files changed, 0 insertions, 180 deletions
diff --git a/third_party/libaeabi-cortexm0/core/cortex-m/uldivmod.S b/third_party/libaeabi-cortexm0/core/cortex-m/uldivmod.S deleted file mode 100644 index 63f060891b..0000000000 --- a/third_party/libaeabi-cortexm0/core/cortex-m/uldivmod.S +++ /dev/null @@ -1,180 +0,0 @@ -/* Runtime ABI for the ARM Cortex-M - * uldivmod.S: unsigned 64 bit division - * - * Copyright (c) 2012 Jörg Mische <bobbl@gmx.de> - * - * Permission to use, copy, modify, and/or distribute this software for any - * purpose with or without fee is hereby granted, provided that the above - * copyright notice and this permission notice appear in all copies. - * - * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES - * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF - * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR - * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES - * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN - * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT - * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. - */ - -#include "software_panic.h" - - - .syntax unified - .text - .code 16 - - - -@ {unsigned long long quotient, unsigned long long remainder} -@ __aeabi_uldivmod(unsigned long long numerator, unsigned long long denominator) -@ -@ Divide r1:r0 by r3:r2 and return the quotient in r1:r0 and the remainder -@ in r3:r2 (all unsigned) -@ - .thumb_func - .section .text.__aeabi_uldivmod - .global __aeabi_uldivmod -__aeabi_uldivmod: - - cmp r3, #0 - bne L_large_denom - cmp r2, #0 - beq L_divison_by_0 - cmp r1, #0 - beq L_fallback_32bits - - - - @ case 1: num >= 2^32 and denom < 2^32 - @ Result might be > 2^32, therefore we first calculate the upper 32 - @ bits of the result. It is done similar to the calculation of the - @ lower 32 bits, but with a denominator that is shifted by 32. - @ Hence the lower 32 bits of the denominator are always 0 and the - @ costly 64 bit shift and sub operations can be replaced by cheap 32 - @ bit operations. - - push {r4, r5, r6, r7, lr} - - @ shift left the denominator until it is greater than the numerator - @ denom(r7:r6) = r3:r2 << 32 - - @ TODO(crosbug.com/p/36128): Loops like this (which occur in several - @ places in this file) are inefficent in ARMv6-m. - - movs r5, #1 @ bitmask - adds r7, r2, #0 @ dont shift if denominator would overflow - bmi L_upper_result - cmp r1, r7 - blo L_upper_result - -L_denom_shift_loop1: - lsl r5, #1 - lsls r7, #1 - bmi L_upper_result @ dont shift if overflow - cmp r1, r7 - bhs L_denom_shift_loop1 - -L_upper_result: - mov r3, r1 - mov r2, r0 - mov r1, #0 @ upper result = 0 - mov r6, #0 - -L_sub_loop1: - orr r1, r5 @ result(r7:r6) |= bitmask(r5) - subs r2, r6 @ num -= denom - sbcs r3, r7 - bhs L_done_sub1 - - eor r1, r5 @ undo add mask - adds r2, r6 @ undo subtract - adc r3, r3, r7 - -L_done_sub1: - lsrs r7, #1 @ denom(r7:r6) >>= 1 - rrx r6, r6 - lsrs r5, #1 @ bitmask(r5) >>= 1 - bne L_sub_loop1 - - rrx r5, r5 - b L_lower_result - - - - @ case 2: division by 0 - @ call __aeabi_ldiv0 - -L_divison_by_0: - b __aeabi_ldiv0 - - - - @ case 3: num < 2^32 and denom < 2^32 - @ fallback to 32 bit division - -L_fallback_32bits: - mov r1, r0 - udiv r0, r0, r2 @ r0 = quotient - mul r3, r0, r2 @ r3 = quotient * divisor - sub r2, r1, r3 @ r2 = remainder - mov r1, #0 - mov r3, #0 - bx lr - - - - @ case 4: denom >= 2^32 - @ result is smaller than 2^32 - -L_large_denom: - push {r4, r5, r6, r7, lr} - - mov r7, r3 - mov r6, r2 - mov r3, r1 - mov r2, r0 - - @ Shift left the denominator until it is greater than the numerator - - mov r1, #0 @ high word of result is 0 - mov r5, #1 @ bitmask - adds r7, #0 @ dont shift if denominator would overflow - bmi L_lower_result - cmp r3, r7 - blo L_lower_result - -L_denom_shift_loop4: - lsl r5, #1 - lsls r6, #1 @ denom(r7:r6) <<= 1 - adcs r7, r7 - bmi L_lower_result @ dont shift if overflow - cmp r3, r7 - bhs L_denom_shift_loop4 - - - -L_lower_result: - movs r0, #0 - -L_sub_loop4: - orr r0, r5 @ result(r1:r0) |= bitmask(r5) - subs r2, r6 @ numerator -= denom - sbcs r3, r7 - bhs L_done_sub4 - - eor r0, r5 @ undo add mask - adds r2, r6 @ undo subtract - adc r3, r3, r7 - -L_done_sub4: - lsrs r7, #1 @ denom(r7:r6) >>= 1 - rrx r6, r6 - lsrs r5, #1 @ bitmask(r5) >>= 1 - bne L_sub_loop4 - - pop {r4, r5, r6, r7, pc} - -__aeabi_ldiv0: - ldr SOFTWARE_PANIC_REASON_REG, =PANIC_SW_DIV_ZERO - mov SOFTWARE_PANIC_INFO_REG, r14 - bl exception_panic |