1 /*===-- divmodsi4.S - 32-bit signed 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 __divmodsi4 (32-bit signed integer divide and 11 * modulus) function for the ARM architecture. A naive digit-by-digit 12 * computation is employed for simplicity. 13 * 14 *===----------------------------------------------------------------------===*/ 15 16 #include "../assembly.h" 17 18 #define ESTABLISH_FRAME \ 19 push {r4-r7, lr} ;\ 20 add r7, sp, #12 21 #define CLEAR_FRAME_AND_RETURN \ 22 pop {r4-r7, pc} 23 24 .syntax unified 25 .text 26 #if __ARM_ARCH_ISA_THUMB == 2 27 .thumb 28 #endif 29 30 @ int __divmodsi4(int divident, int divisor, int *remainder) 31 @ Calculate the quotient and remainder of the (signed) division. The return 32 @ value is the quotient, the remainder is placed in the variable. 33 34 .p2align 3 35 #if __ARM_ARCH_ISA_THUMB == 2 36 DEFINE_COMPILERRT_THUMB_FUNCTION(__divmodsi4) 37 #else 38 DEFINE_COMPILERRT_FUNCTION(__divmodsi4) 39 #endif 40 #if __ARM_ARCH_EXT_IDIV__ 41 tst r1, r1 42 beq LOCAL_LABEL(divzero) 43 mov r3, r0 44 sdiv r0, r3, r1 45 mls r1, r0, r1, r3 46 str r1, [r2] 47 bx lr 48 LOCAL_LABEL(divzero): 49 mov r0, #0 50 bx lr 51 #else 52 ESTABLISH_FRAME 53 // Set aside the sign of the quotient and modulus, and the address for the 54 // modulus. 55 eor r4, r0, r1 56 mov r5, r0 57 mov r6, r2 58 // Take the absolute value of a and b via abs(x) = (x^(x >> 31)) - (x >> 31). 59 eor ip, r0, r0, asr #31 60 eor lr, r1, r1, asr #31 61 sub r0, ip, r0, asr #31 62 sub r1, lr, r1, asr #31 63 // Unsigned divmod: 64 bl SYMBOL_NAME(__udivmodsi4) 65 // Apply the sign of quotient and modulus 66 ldr r1, [r6] 67 eor r0, r0, r4, asr #31 68 eor r1, r1, r5, asr #31 69 sub r0, r0, r4, asr #31 70 sub r1, r1, r5, asr #31 71 str r1, [r6] 72 CLEAR_FRAME_AND_RETURN 73 #endif 74 END_COMPILERRT_FUNCTION(__divmodsi4) 75 76 NO_EXEC_STACK_DIRECTIVE 77 78
