137a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan/* ===-- floattidf.c - Implement __floattidf -------------------------------=== 237a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * 337a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * The LLVM Compiler Infrastructure 437a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * 59ad441ffec97db647fee3725b3424284fb913e14Howard Hinnant * This file is dual licensed under the MIT and the University of Illinois Open 69ad441ffec97db647fee3725b3424284fb913e14Howard Hinnant * Source Licenses. See LICENSE.TXT for details. 737a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * 837a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * ===----------------------------------------------------------------------=== 937a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * 1037a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * This file implements __floattidf for the compiler_rt library. 1137a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * 1237a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * ===----------------------------------------------------------------------=== 13c58a43648cd6121c51a2e795a28e2ef90d7813e6Pirama Arumuga Nainar */ 14b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 15b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar#include "int_lib.h" 16b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 172d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines#ifdef CRT_HAS_128BIT 187f2d7c75e713d778106d01a54e7aef40227bbf2dChandler Carruth 1937a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan/* Returns: convert a to a double, rounding toward even.*/ 20b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 21c58a43648cd6121c51a2e795a28e2ef90d7813e6Pirama Arumuga Nainar/* Assumption: double is a IEEE 64 bit floating point type 2237a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * ti_int is a 128 bit integral type 2337a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan */ 24b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 25c58a43648cd6121c51a2e795a28e2ef90d7813e6Pirama Arumuga Nainar/* seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm */ 26b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 272d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen HinesCOMPILER_RT_ABI double 28b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar__floattidf(ti_int a) 29b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar{ 30b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar if (a == 0) 31b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar return 0.0; 32b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar const unsigned N = sizeof(ti_int) * CHAR_BIT; 33b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar const ti_int s = a >> (N-1); 34b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar a = (a ^ s) - s; 3537a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan int sd = N - __clzti2(a); /* number of significant digits */ 3637a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan int e = sd - 1; /* exponent */ 37b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar if (sd > DBL_MANT_DIG) 38b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar { 3937a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan /* start: 0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQxxxxxxxxxxxxxxxxxx 4037a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * finish: 000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQR 4137a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * 12345678901234567890123456 4237a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * 1 = msb 1 bit 4337a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * P = bit DBL_MANT_DIG-1 bits to the right of 1 4437a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * Q = bit DBL_MANT_DIG bits to the right of 1 4537a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * R = "or" of all bits to the right of Q 4637a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan */ 47b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar switch (sd) 48b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar { 49b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar case DBL_MANT_DIG + 1: 50b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar a <<= 1; 51b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar break; 52b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar case DBL_MANT_DIG + 2: 53b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar break; 54b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar default: 55b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar a = ((tu_int)a >> (sd - (DBL_MANT_DIG+2))) | 56b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar ((a & ((tu_int)(-1) >> ((N + DBL_MANT_DIG+2) - sd))) != 0); 57b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar }; 5837a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan /* finish: */ 5937a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan a |= (a & 4) != 0; /* Or P into R */ 6037a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan ++a; /* round - this step may add a significant bit */ 6137a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan a >>= 2; /* dump Q and R */ 6237a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan /* a is now rounded to DBL_MANT_DIG or DBL_MANT_DIG+1 bits */ 63b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar if (a & ((tu_int)1 << DBL_MANT_DIG)) 64b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar { 65b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar a >>= 1; 66b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar ++e; 67b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar } 6837a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan /* a is now rounded to DBL_MANT_DIG bits */ 69b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar } 70b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar else 71b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar { 72b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar a <<= (DBL_MANT_DIG - sd); 7337a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan /* a is now rounded to DBL_MANT_DIG bits */ 74b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar } 75b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar double_bits fb; 76aabd961cc27f5d05f441375e5ba4242d63fea11fEdward O'Callaghan fb.u.s.high = ((su_int)s & 0x80000000) | /* sign */ 7737a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan ((e + 1023) << 20) | /* exponent */ 7837a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan ((su_int)(a >> 32) & 0x000FFFFF); /* mantissa-high */ 79aabd961cc27f5d05f441375e5ba4242d63fea11fEdward O'Callaghan fb.u.s.low = (su_int)a; /* mantissa-low */ 80b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar return fb.f; 81b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar} 82b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 832d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines#endif /* CRT_HAS_128BIT */ 84