1229109Sed/*===-- muloti4.c - Implement __muloti4 -----------------------------------=== 2229109Sed * 3229109Sed * The LLVM Compiler Infrastructure 4229109Sed * 5229109Sed * This file is dual licensed under the MIT and the University of Illinois Open 6229109Sed * Source Licenses. See LICENSE.TXT for details. 7229109Sed * 8229109Sed * ===----------------------------------------------------------------------=== 9229109Sed * 10229109Sed * This file implements __muloti4 for the compiler_rt library. 11229109Sed * 12229109Sed * ===----------------------------------------------------------------------=== 13229109Sed */ 14229109Sed 15263560Sdim#include "int_lib.h" 16263560Sdim 17263764Sdim#ifdef CRT_HAS_128BIT 18229109Sed 19229109Sed/* Returns: a * b */ 20229109Sed 21229109Sed/* Effects: sets *overflow to 1 if a * b overflows */ 22229109Sed 23229109Sedti_int 24229109Sed__muloti4(ti_int a, ti_int b, int* overflow) 25229109Sed{ 26229109Sed const int N = (int)(sizeof(ti_int) * CHAR_BIT); 27229109Sed const ti_int MIN = (ti_int)1 << (N-1); 28229109Sed const ti_int MAX = ~MIN; 29229109Sed *overflow = 0; 30229109Sed ti_int result = a * b; 31229109Sed if (a == MIN) 32229109Sed { 33229109Sed if (b != 0 && b != 1) 34229109Sed *overflow = 1; 35229109Sed return result; 36229109Sed } 37229109Sed if (b == MIN) 38229109Sed { 39229109Sed if (a != 0 && a != 1) 40229109Sed *overflow = 1; 41229109Sed return result; 42229109Sed } 43229109Sed ti_int sa = a >> (N - 1); 44229109Sed ti_int abs_a = (a ^ sa) - sa; 45229109Sed ti_int sb = b >> (N - 1); 46229109Sed ti_int abs_b = (b ^ sb) - sb; 47229109Sed if (abs_a < 2 || abs_b < 2) 48229109Sed return result; 49229109Sed if (sa == sb) 50229109Sed { 51229109Sed if (abs_a > MAX / abs_b) 52229109Sed *overflow = 1; 53229109Sed } 54229109Sed else 55229109Sed { 56229109Sed if (abs_a > MIN / -abs_b) 57229109Sed *overflow = 1; 58229109Sed } 59229109Sed return result; 60229109Sed} 61229109Sed 62263764Sdim#endif /* CRT_HAS_128BIT */ 63