1/*===-- udivmodsi4.S - 32-bit unsigned integer divide and modulus ---------===// 2 * 3 * The LLVM Compiler Infrastructure 4 * 5 * This file is dual licensed under the MIT and the University of Illinois Open 6 * Source Licenses. See LICENSE.TXT for details. 7 * 8 *===----------------------------------------------------------------------===// 9 * 10 * This file implements the __udivmodsi4 (32-bit unsigned integer divide and 11 * modulus) function for the ARM 32-bit architecture. 12 * 13 *===----------------------------------------------------------------------===*/ 14 15#include "../assembly.h" 16 17 .syntax unified 18 .text 19 20#if __ARM_ARCH_ISA_THUMB == 2 21 .thumb 22#endif 23 24@ unsigned int __udivmodsi4(unsigned int divident, unsigned int divisor, 25@ unsigned int *remainder) 26@ Calculate the quotient and remainder of the (unsigned) division. The return 27@ value is the quotient, the remainder is placed in the variable. 28 29 .p2align 2 30DEFINE_COMPILERRT_FUNCTION(__udivmodsi4) 31#if __ARM_ARCH_EXT_IDIV__ 32 tst r1, r1 33 beq LOCAL_LABEL(divby0) 34 mov r3, r0 35 udiv r0, r3, r1 36 mls r1, r0, r1, r3 37 str r1, [r2] 38 bx lr 39#else 40 cmp r1, #1 41 bcc LOCAL_LABEL(divby0) 42 beq LOCAL_LABEL(divby1) 43 cmp r0, r1 44 bcc LOCAL_LABEL(quotient0) 45 /* 46 * Implement division using binary long division algorithm. 47 * 48 * r0 is the numerator, r1 the denominator. 49 * 50 * The code before JMP computes the correct shift I, so that 51 * r0 and (r1 << I) have the highest bit set in the same position. 52 * At the time of JMP, ip := .Ldiv0block - 12 * I. 53 * This depends on the fixed instruction size of block. 54 * For ARM mode, this is 12 Bytes, for THUMB mode 14 Bytes. 55 * 56 * block(shift) implements the test-and-update-quotient core. 57 * It assumes (r0 << shift) can be computed without overflow and 58 * that (r0 << shift) < 2 * r1. The quotient is stored in r3. 59 */ 60 61# ifdef __ARM_FEATURE_CLZ 62 clz ip, r0 63 clz r3, r1 64 /* r0 >= r1 implies clz(r0) <= clz(r1), so ip <= r3. */ 65 sub r3, r3, ip 66# if __ARM_ARCH_ISA_THUMB == 2 67 adr ip, LOCAL_LABEL(div0block) + 1 68 sub ip, ip, r3, lsl #1 69# else 70 adr ip, LOCAL_LABEL(div0block) 71# endif 72 sub ip, ip, r3, lsl #2 73 sub ip, ip, r3, lsl #3 74 mov r3, #0 75 bx ip 76# else 77# if __ARM_ARCH_ISA_THUMB == 2 78# error THUMB mode requires CLZ or UDIV 79# endif 80 str r4, [sp, #-8]! 81 82 mov r4, r0 83 adr ip, LOCAL_LABEL(div0block) 84 85 lsr r3, r4, #16 86 cmp r3, r1 87 movhs r4, r3 88 subhs ip, ip, #(16 * 12) 89 90 lsr r3, r4, #8 91 cmp r3, r1 92 movhs r4, r3 93 subhs ip, ip, #(8 * 12) 94 95 lsr r3, r4, #4 96 cmp r3, r1 97 movhs r4, r3 98 subhs ip, #(4 * 12) 99 100 lsr r3, r4, #2 101 cmp r3, r1 102 movhs r4, r3 103 subhs ip, ip, #(2 * 12) 104 105 /* Last block, no need to update r3 or r4. */ 106 cmp r1, r4, lsr #1 107 subls ip, ip, #(1 * 12) 108 109 ldr r4, [sp], #8 /* restore r4, we are done with it. */ 110 mov r3, #0 111 112 JMP(ip) 113# endif 114 115#define IMM # 116 117#define block(shift) \ 118 cmp r0, r1, lsl IMM shift; \ 119 ITT(hs); \ 120 WIDE(addhs) r3, r3, IMM (1 << shift); \ 121 WIDE(subhs) r0, r0, r1, lsl IMM shift 122 123 block(31) 124 block(30) 125 block(29) 126 block(28) 127 block(27) 128 block(26) 129 block(25) 130 block(24) 131 block(23) 132 block(22) 133 block(21) 134 block(20) 135 block(19) 136 block(18) 137 block(17) 138 block(16) 139 block(15) 140 block(14) 141 block(13) 142 block(12) 143 block(11) 144 block(10) 145 block(9) 146 block(8) 147 block(7) 148 block(6) 149 block(5) 150 block(4) 151 block(3) 152 block(2) 153 block(1) 154LOCAL_LABEL(div0block): 155 block(0) 156 157 str r0, [r2] 158 mov r0, r3 159 JMP(lr) 160 161LOCAL_LABEL(quotient0): 162 str r0, [r2] 163 mov r0, #0 164 JMP(lr) 165 166LOCAL_LABEL(divby1): 167 mov r3, #0 168 str r3, [r2] 169 JMP(lr) 170#endif /* __ARM_ARCH_EXT_IDIV__ */ 171 172LOCAL_LABEL(divby0): 173 mov r0, #0 174#ifdef __ARM_EABI__ 175 b __aeabi_idiv0 176#else 177 JMP(lr) 178#endif 179 180END_COMPILERRT_FUNCTION(__udivmodsi4) 181