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Diffstat (limited to 'lib/arm/divmodsi4.S')
-rw-r--r-- | lib/arm/divmodsi4.S | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/lib/arm/divmodsi4.S b/lib/arm/divmodsi4.S new file mode 100644 index 0000000..cec39a7 --- /dev/null +++ b/lib/arm/divmodsi4.S @@ -0,0 +1,47 @@ +/*===-- divmodsi4.S - 32-bit signed integer divide and modulus ------------===// + * + * The LLVM Compiler Infrastructure + * + * This file is dual licensed under the MIT and the University of Illinois Open + * Source Licenses. See LICENSE.TXT for details. + * + *===----------------------------------------------------------------------===// + * + * This file implements the __divmodsi4 (32-bit signed integer divide and + * modulus) function for the ARM architecture. A naive digit-by-digit + * computation is employed for simplicity. + * + *===----------------------------------------------------------------------===*/ + +#include "../assembly.h" + +#define ESTABLISH_FRAME \ + push {r4-r7, lr} ;\ + add r7, sp, #12 +#define CLEAR_FRAME_AND_RETURN \ + pop {r4-r7, pc} + +.syntax unified +.align 3 +DEFINE_COMPILERRT_FUNCTION(__divmodsi4) + ESTABLISH_FRAME +// Set aside the sign of the quotient and modulus, and the address for the +// modulus. + eor r4, r0, r1 + mov r5, r0 + mov r6, r2 +// Take the absolute value of a and b via abs(x) = (x^(x >> 31)) - (x >> 31). + eor ip, r0, r0, asr #31 + eor lr, r1, r1, asr #31 + sub r0, ip, r0, asr #31 + sub r1, lr, r1, asr #31 +// Unsigned divmod: + bl SYMBOL_NAME(__udivmodsi4) +// Apply the sign of quotient and modulus + ldr r1, [r6] + eor r0, r0, r4, asr #31 + eor r1, r1, r5, asr #31 + sub r0, r0, r4, asr #31 + sub r1, r1, r5, asr #31 + str r1, [r6] + CLEAR_FRAME_AND_RETURN |