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 #if __ARM_ARCH_ISA_THUMB == 2 20 .thumb 21 #endif 22 23 @ unsigned int __umodsi3(unsigned int divident, unsigned int divisor) 24 @ Calculate and return the remainder of the (unsigned) division. 25 26 .p2align 2 27 #if __ARM_ARCH_ISA_THUMB == 2 28 DEFINE_COMPILERRT_THUMB_FUNCTION(__umodsi3) 29 #else 30 DEFINE_COMPILERRT_FUNCTION(__umodsi3) 31 #endif 32 #if __ARM_ARCH_EXT_IDIV__ 33 tst r1, r1 34 beq LOCAL_LABEL(divby0) 35 udiv r2, r0, r1 36 mls r0, r2, r1, r0 37 bx lr 38 #else 39 cmp r1, #1 40 bcc LOCAL_LABEL(divby0) 41 ITT(eq) 42 moveq r0, #0 43 JMPc(lr, eq) 44 cmp r0, r1 45 IT(cc) 46 JMPc(lr, cc) 47 /* 48 * Implement division using binary long division algorithm. 49 * 50 * r0 is the numerator, r1 the denominator. 51 * 52 * The code before JMP computes the correct shift I, so that 53 * r0 and (r1 << I) have the highest bit set in the same position. 54 * At the time of JMP, ip := .Ldiv0block - 8 * I. 55 * This depends on the fixed instruction size of block. 56 * For ARM mode, this is 8 Bytes, for THUMB mode 10 Bytes. 57 * 58 * block(shift) implements the test-and-update-quotient core. 59 * It assumes (r0 << shift) can be computed without overflow and 60 * that (r0 << shift) < 2 * r1. The quotient is stored in r3. 61 */ 62 63 # ifdef __ARM_FEATURE_CLZ 64 clz ip, r0 65 clz r3, r1 66 /* r0 >= r1 implies clz(r0) <= clz(r1), so ip <= r3. */ 67 sub r3, r3, ip 68 # if __ARM_ARCH_ISA_THUMB == 2 69 adr ip, LOCAL_LABEL(div0block) + 1 70 sub ip, ip, r3, lsl #1 71 # else 72 adr ip, LOCAL_LABEL(div0block) 73 # endif 74 sub ip, ip, r3, lsl #3 75 bx ip 76 # else 77 # if __ARM_ARCH_ISA_THUMB == 2 78 # error THUMB mode requires CLZ or UDIV 79 # endif 80 mov r2, r0 81 adr ip, LOCAL_LABEL(div0block) 82 83 lsr r3, r2, #16 84 cmp r3, r1 85 movhs r2, r3 86 subhs ip, ip, #(16 * 8) 87 88 lsr r3, r2, #8 89 cmp r3, r1 90 movhs r2, r3 91 subhs ip, ip, #(8 * 8) 92 93 lsr r3, r2, #4 94 cmp r3, r1 95 movhs r2, r3 96 subhs ip, #(4 * 8) 97 98 lsr r3, r2, #2 99 cmp r3, r1 100 movhs r2, r3 101 subhs ip, ip, #(2 * 8) 102 103 /* Last block, no need to update r2 or r3. */ 104 cmp r1, r2, lsr #1 105 subls ip, ip, #(1 * 8) 106 107 JMP(ip) 108 # endif 109 110 #define IMM # 111 112 #define block(shift) \ 113 cmp r0, r1, lsl IMM shift; \ 114 IT(hs); \ 115 WIDE(subhs) r0, r0, r1, lsl IMM shift 116 117 block(31) 118 block(30) 119 block(29) 120 block(28) 121 block(27) 122 block(26) 123 block(25) 124 block(24) 125 block(23) 126 block(22) 127 block(21) 128 block(20) 129 block(19) 130 block(18) 131 block(17) 132 block(16) 133 block(15) 134 block(14) 135 block(13) 136 block(12) 137 block(11) 138 block(10) 139 block(9) 140 block(8) 141 block(7) 142 block(6) 143 block(5) 144 block(4) 145 block(3) 146 block(2) 147 block(1) 148 LOCAL_LABEL(div0block): 149 block(0) 150 JMP(lr) 151 #endif /* __ARM_ARCH_EXT_IDIV__ */ 152 153 LOCAL_LABEL(divby0): 154 mov r0, #0 155 #ifdef __ARM_EABI__ 156 b __aeabi_idiv0 157 #else 158 JMP(lr) 159 #endif 160 161 END_COMPILERRT_FUNCTION(__umodsi3) 162
