1 // SPDX-License-Identifier: GPL-2.0-only 2 /* IEEE754 floating point arithmetic 3 * double precision: common utilities 4 */ 5 /* 6 * MIPS floating point support 7 * Copyright (C) 1994-2000 Algorithmics Ltd. 8 */ 9 10 #include "ieee754dp.h" 11 12 int ieee754dp_tint(union ieee754dp x) 13 { 14 u64 residue; 15 int round; 16 int sticky; 17 int odd; 18 19 COMPXDP; 20 21 ieee754_clearcx(); 22 23 EXPLODEXDP; 24 FLUSHXDP; 25 26 switch (xc) { 27 case IEEE754_CLASS_SNAN: 28 case IEEE754_CLASS_QNAN: 29 ieee754_setcx(IEEE754_INVALID_OPERATION); 30 return ieee754si_indef(); 31 32 case IEEE754_CLASS_INF: 33 ieee754_setcx(IEEE754_INVALID_OPERATION); 34 return ieee754si_overflow(xs); 35 36 case IEEE754_CLASS_ZERO: 37 return 0; 38 39 case IEEE754_CLASS_DNORM: 40 case IEEE754_CLASS_NORM: 41 break; 42 } 43 if (xe > 31) { 44 /* Set invalid. We will only use overflow for floating 45 point overflow */ 46 ieee754_setcx(IEEE754_INVALID_OPERATION); 47 return ieee754si_overflow(xs); 48 } 49 /* oh gawd */ 50 if (xe > DP_FBITS) { 51 xm <<= xe - DP_FBITS; 52 } else if (xe < DP_FBITS) { 53 if (xe < -1) { 54 residue = xm; 55 round = 0; 56 sticky = residue != 0; 57 xm = 0; 58 } else { 59 residue = xm << (64 - DP_FBITS + xe); 60 round = (residue >> 63) != 0; 61 sticky = (residue << 1) != 0; 62 xm >>= DP_FBITS - xe; 63 } 64 /* Note: At this point upper 32 bits of xm are guaranteed 65 to be zero */ 66 odd = (xm & 0x1) != 0x0; 67 switch (ieee754_csr.rm) { 68 case FPU_CSR_RN: 69 if (round && (sticky || odd)) 70 xm++; 71 break; 72 case FPU_CSR_RZ: 73 break; 74 case FPU_CSR_RU: /* toward +Infinity */ 75 if ((round || sticky) && !xs) 76 xm++; 77 break; 78 case FPU_CSR_RD: /* toward -Infinity */ 79 if ((round || sticky) && xs) 80 xm++; 81 break; 82 } 83 /* look for valid corner case 0x80000000 */ 84 if ((xm >> 31) != 0 && (xs == 0 || xm != 0x80000000)) { 85 /* This can happen after rounding */ 86 ieee754_setcx(IEEE754_INVALID_OPERATION); 87 return ieee754si_overflow(xs); 88 } 89 if (round || sticky) 90 ieee754_setcx(IEEE754_INEXACT); 91 } 92 if (xs) 93 return -xm; 94 else 95 return xm; 96 } 97