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 "crt_glue.h" 16 17 /* Returns: a * b */ 18 19 static 20 ti_int __mulddi3(du_int a,du_int b)21__mulddi3(du_int a, du_int b) 22 { 23 twords r; 24 const int bits_in_dword_2 = (int)(sizeof(di_int) * CHAR_BIT) / 2; 25 const du_int lower_mask = (du_int)~0 >> bits_in_dword_2; 26 r.s.low = (a & lower_mask) * (b & lower_mask); 27 du_int t = r.s.low >> bits_in_dword_2; 28 r.s.low &= lower_mask; 29 t += (a >> bits_in_dword_2) * (b & lower_mask); 30 r.s.low += (t & lower_mask) << bits_in_dword_2; 31 r.s.high = t >> bits_in_dword_2; 32 t = r.s.low >> bits_in_dword_2; 33 r.s.low &= lower_mask; 34 t += (b >> bits_in_dword_2) * (a & lower_mask); 35 r.s.low += (t & lower_mask) << bits_in_dword_2; 36 r.s.high += t >> bits_in_dword_2; 37 r.s.high += (a >> bits_in_dword_2) * (b >> bits_in_dword_2); 38 return r.all; 39 } 40 41 /* Returns: a * b */ 42 43 ti_int __multi3(ti_int a,ti_int b)44__multi3(ti_int a, ti_int b) 45 { 46 twords x; 47 x.all = a; 48 twords y; 49 y.all = b; 50 twords r; 51 r.all = __mulddi3(x.s.low, y.s.low); 52 r.s.high += x.s.high * y.s.low + x.s.low * y.s.high; 53 return r.all; 54 } 55