1/*===-- umodsi3.S - 32-bit unsigned integer 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 __umodsi3 (32-bit unsigned integer modulus) 11 * function for the ARM 32-bit architecture. 12 * 13 *===----------------------------------------------------------------------===*/ 14 15#include "../assembly.h" 16 17 .syntax unified 18 .text 19 20@ unsigned int __umodsi3(unsigned int divident, unsigned int divisor) 21@ Calculate and return the remainder of the (unsigned) division. 22 23 .p2align 2 24DEFINE_COMPILERRT_FUNCTION(__umodsi3) 25#if __ARM_ARCH_EXT_IDIV__ 26 tst r1, r1 27 beq LOCAL_LABEL(divby0) 28 udiv r2, r0, r1 29 mls r0, r2, r1, r0 30 bx lr 31#else 32 cmp r1, #1 33 bcc LOCAL_LABEL(divby0) 34 ITT(eq) 35 moveq r0, #0 36 JMPc(lr, eq) 37 cmp r0, r1 38 IT(cc) 39 JMPc(lr, cc) 40 /* 41 * Implement division using binary long division algorithm. 42 * 43 * r0 is the numerator, r1 the denominator. 44 * 45 * The code before JMP computes the correct shift I, so that 46 * r0 and (r1 << I) have the highest bit set in the same position. 47 * At the time of JMP, ip := .Ldiv0block - 8 * I. 48 * This depends on the fixed instruction size of block. 49 * For ARM mode, this is 8 Bytes, for THUMB mode 10 Bytes. 50 * 51 * block(shift) implements the test-and-update-quotient core. 52 * It assumes (r0 << shift) can be computed without overflow and 53 * that (r0 << shift) < 2 * r1. The quotient is stored in r3. 54 */ 55 56# ifdef __ARM_FEATURE_CLZ 57 clz ip, r0 58 clz r3, r1 59 /* r0 >= r1 implies clz(r0) <= clz(r1), so ip <= r3. */ 60 sub r3, r3, ip 61 adr ip, LOCAL_LABEL(div0block) 62 sub ip, ip, r3, lsl #3 63 bx ip 64# else 65 mov r2, r0 66 adr ip, LOCAL_LABEL(div0block) 67 68 lsr r3, r2, #16 69 cmp r3, r1 70 movhs r2, r3 71 subhs ip, ip, #(16 * 8) 72 73 lsr r3, r2, #8 74 cmp r3, r1 75 movhs r2, r3 76 subhs ip, ip, #(8 * 8) 77 78 lsr r3, r2, #4 79 cmp r3, r1 80 movhs r2, r3 81 subhs ip, #(4 * 8) 82 83 lsr r3, r2, #2 84 cmp r3, r1 85 movhs r2, r3 86 subhs ip, ip, #(2 * 8) 87 88 /* Last block, no need to update r2 or r3. */ 89 cmp r1, r2, lsr #1 90 subls ip, ip, #(1 * 8) 91 92 JMP(ip) 93# endif 94 95#define IMM # 96 97#define block(shift) \ 98 cmp r0, r1, lsl IMM shift; \ 99 IT(hs); \ 100 WIDE(subhs) r0, r0, r1, lsl IMM shift 101 102 block(31) 103 block(30) 104 block(29) 105 block(28) 106 block(27) 107 block(26) 108 block(25) 109 block(24) 110 block(23) 111 block(22) 112 block(21) 113 block(20) 114 block(19) 115 block(18) 116 block(17) 117 block(16) 118 block(15) 119 block(14) 120 block(13) 121 block(12) 122 block(11) 123 block(10) 124 block(9) 125 block(8) 126 block(7) 127 block(6) 128 block(5) 129 block(4) 130 block(3) 131 block(2) 132 block(1) 133LOCAL_LABEL(div0block): 134 block(0) 135 JMP(lr) 136#endif /* __ARM_ARCH_EXT_IDIV__ */ 137 138LOCAL_LABEL(divby0): 139 mov r0, #0 140#ifdef __ARM_EABI__ 141 b __aeabi_idiv0 142#else 143 JMP(lr) 144#endif 145 146END_COMPILERRT_FUNCTION(__umodsi3) 147