1 /* ===-- multi3.c - Implement __multi3 -------------------------------------=== 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 __multi3 for the compiler_rt library. 11 * 12 * ===----------------------------------------------------------------------=== 13 */ 14 15 #include "int_lib.h" 16 17 #ifdef CRT_HAS_128BIT 18 19 /* Returns: a * b */ 20 21 static 22 ti_int 23 __mulddi3(du_int a, du_int b) 24 { 25 twords r; 26 const int bits_in_dword_2 = (int)(sizeof(di_int) * CHAR_BIT) / 2; 27 const du_int lower_mask = (du_int)~0 >> bits_in_dword_2; 28 r.s.low = (a & lower_mask) * (b & lower_mask); 29 du_int t = r.s.low >> bits_in_dword_2; 30 r.s.low &= lower_mask; 31 t += (a >> bits_in_dword_2) * (b & lower_mask); 32 r.s.low += (t & lower_mask) << bits_in_dword_2; 33 r.s.high = t >> bits_in_dword_2; 34 t = r.s.low >> bits_in_dword_2; 35 r.s.low &= lower_mask; 36 t += (b >> bits_in_dword_2) * (a & lower_mask); 37 r.s.low += (t & lower_mask) << bits_in_dword_2; 38 r.s.high += t >> bits_in_dword_2; 39 r.s.high += (a >> bits_in_dword_2) * (b >> bits_in_dword_2); 40 return r.all; 41 } 42 43 /* Returns: a * b */ 44 45 COMPILER_RT_ABI ti_int 46 __multi3(ti_int a, ti_int b) 47 { 48 twords x; 49 x.all = a; 50 twords y; 51 y.all = b; 52 twords r; 53 r.all = __mulddi3(x.s.low, y.s.low); 54 r.s.high += x.s.high * y.s.low + x.s.low * y.s.high; 55 return r.all; 56 } 57 58 #endif /* CRT_HAS_128BIT */ 59
