| [9] | 1 | /*
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| 2 | (c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
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| 3 | See the copyright notice in the ACK home directory, in the file "Copyright".
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| 4 | */
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| 5 |
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| 6 | /* $Header: /cvsup/minix/src/lib/float/compact.c,v 1.1.1.1 2005/04/21 14:56:10 beng Exp $ */
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| 7 |
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| 8 | /*
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| 9 | COMPACT EXTEND FORMAT INTO FLOAT OF PROPER SIZE
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| 10 | */
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| 11 |
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| 12 | # include "FP_bias.h"
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| 13 | # include "FP_shift.h"
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| 14 | # include "FP_trap.h"
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| 15 | # include "FP_types.h"
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| 16 | # include "get_put.h"
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| 17 |
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| 18 | void
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| 19 | compact(f,to,size)
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| 20 | EXTEND *f;
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| 21 | unsigned long *to;
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| 22 | int size;
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| 23 | {
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| 24 | int error = 0;
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| 25 |
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| 26 | if (size == sizeof(DOUBLE)) {
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| 27 | /*
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| 28 | * COMPACT EXTENDED INTO DOUBLE
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| 29 | */
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| 30 | DOUBLE *DBL = (DOUBLE *) (void *) to;
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| 31 |
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| 32 | if ((f->m1|(f->m2 & DBL_ZERO)) == 0L) {
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| 33 | zrf8(DBL);
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| 34 | return;
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| 35 | }
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| 36 | f->exp += DBL_BIAS; /* restore proper bias */
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| 37 | if (f->exp > DBL_MAX) {
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| 38 | dbl_over: trap(EFOVFL);
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| 39 | f->exp = DBL_MAX+1;
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| 40 | f->m1 = 0;
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| 41 | f->m2 = 0;
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| 42 | if (error++)
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| 43 | return;
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| 44 | }
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| 45 | else if (f->exp < DBL_MIN) {
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| 46 | b64_rsft(&(f->mantissa));
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| 47 | if (f->exp < 0) {
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| 48 | b64_sft(&(f->mantissa), -f->exp);
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| 49 | f->exp = 0;
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| 50 | }
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| 51 | /* underflow ??? */
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| 52 | }
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| 53 |
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| 54 | /* local CAST conversion */
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| 55 |
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| 56 | /* because of special format shift only 10 bits */
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| 57 | /* bit shift mantissa 10 bits */
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| 58 |
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| 59 | /* first align within words, then do store operation */
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| 60 |
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| 61 | DBL->d[0] = f->m1 >> DBL_RUNPACK; /* plus 22 == 32 */
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| 62 | DBL->d[1] = f->m2 >> DBL_RUNPACK; /* plus 22 == 32 */
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| 63 | DBL->d[1] |= (f->m1 << DBL_LUNPACK); /* plus 10 == 32 */
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| 64 |
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| 65 | /* if not exact then round to nearest */
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| 66 | /* on a tie, round to even */
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| 67 |
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| 68 | #ifdef EXCEPTION_INEXACT
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| 69 | if ((f->m2 & DBL_EXACT) != 0) {
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| 70 | INEXACT();
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| 71 | #endif
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| 72 | if (((f->m2 & DBL_EXACT) > DBL_ROUNDUP)
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| 73 | || ((f->m2 & DBL_EXACT) == DBL_ROUNDUP
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| 74 | && (f->m2 & (DBL_ROUNDUP << 1)))) {
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| 75 | DBL->d[1]++; /* rounding up */
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| 76 | if (DBL->d[1] == 0L) { /* carry out */
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| 77 | DBL->d[0]++;
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| 78 |
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| 79 | if (f->exp == 0 && (DBL->d[0] & ~DBL_MASK)) {
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| 80 | f->exp++;
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| 81 | }
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| 82 | if (DBL->d[0] & DBL_CARRYOUT) { /* carry out */
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| 83 | if (DBL->d[0] & 01)
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| 84 | DBL->d[1] = CARRYBIT;
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| 85 | DBL->d[0] >>= 1;
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| 86 | f->exp++;
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| 87 | }
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| 88 | }
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| 89 | /* check for overflow */
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| 90 | if (f->exp > DBL_MAX)
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| 91 | goto dbl_over;
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| 92 | }
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| 93 | #ifdef EXCEPTION_INEXACT
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| 94 | }
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| 95 | #endif
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| 96 |
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| 97 | /*
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| 98 | * STORE EXPONENT AND SIGN:
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| 99 | *
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| 100 | * 1) clear leading bits (B4-B15)
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| 101 | * 2) shift and store exponent
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| 102 | */
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| 103 |
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| 104 | DBL->d[0] &= DBL_MASK;
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| 105 | DBL->d[0] |=
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| 106 | ((long) (f->exp << DBL_EXPSHIFT) << EXP_STORE);
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| 107 | if (f->sign)
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| 108 | DBL->d[0] |= CARRYBIT;
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| 109 |
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| 110 | /*
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| 111 | * STORE MANTISSA
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| 112 | */
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| 113 |
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| 114 | #if FL_MSL_AT_LOW_ADDRESS
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| 115 | put4(DBL->d[0], (char *) &DBL->d[0]);
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| 116 | put4(DBL->d[1], (char *) &DBL->d[1]);
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| 117 | #else
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| 118 | { unsigned long l;
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| 119 | put4(DBL->d[1], (char *) &l);
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| 120 | put4(DBL->d[0], (char *) &DBL->d[1]);
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| 121 | DBL->d[0] = l;
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| 122 | }
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| 123 | #endif
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| 124 | }
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| 125 | else {
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| 126 | /*
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| 127 | * COMPACT EXTENDED INTO FLOAT
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| 128 | */
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| 129 | SINGLE *SGL;
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| 130 |
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| 131 | /* local CAST conversion */
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| 132 | SGL = (SINGLE *) (void *) to;
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| 133 | if ((f->m1 & SGL_ZERO) == 0L) {
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| 134 | *SGL = 0L;
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| 135 | return;
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| 136 | }
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| 137 | f->exp += SGL_BIAS; /* restore bias */
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| 138 | if (f->exp > SGL_MAX) {
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| 139 | sgl_over: trap(EFOVFL);
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| 140 | f->exp = SGL_MAX+1;
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| 141 | f->m1 = 0L;
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| 142 | f->m2 = 0L;
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| 143 | if (error++)
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| 144 | return;
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| 145 | }
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| 146 | else if (f->exp < SGL_MIN) {
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| 147 | b64_rsft(&(f->mantissa));
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| 148 | if (f->exp < 0) {
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| 149 | b64_sft(&(f->mantissa), -f->exp);
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| 150 | f->exp = 0;
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| 151 | }
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| 152 | /* underflow ??? */
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| 153 | }
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| 154 |
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| 155 | /* shift mantissa and store */
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| 156 | *SGL = (f->m1 >> SGL_RUNPACK);
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| 157 |
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| 158 | /* check for rounding to nearest */
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| 159 | /* on a tie, round to even */
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| 160 | #ifdef EXCEPTION_INEXACT
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| 161 | if (f->m2 != 0 ||
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| 162 | (f->m1 & SGL_EXACT) != 0L) {
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| 163 | INEXACT();
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| 164 | #endif
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| 165 | if (((f->m1 & SGL_EXACT) > SGL_ROUNDUP)
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| 166 | || ((f->m1 & SGL_EXACT) == SGL_ROUNDUP
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| 167 | && (f->m1 & (SGL_ROUNDUP << 1)))) {
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| 168 | (*SGL)++;
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| 169 | if (f->exp == 0 && (*SGL & ~SGL_MASK)) {
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| 170 | f->exp++;
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| 171 | }
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| 172 | /* check normal */
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| 173 | if (*SGL & SGL_CARRYOUT) {
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| 174 | *SGL >>= 1;
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| 175 | f->exp++;
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| 176 | }
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| 177 | if (f->exp > SGL_MAX)
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| 178 | goto sgl_over;
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| 179 | }
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| 180 | #ifdef EXCEPTION_INEXACT
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| 181 | }
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| 182 | #endif
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| 183 |
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| 184 | /*
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| 185 | * STORE EXPONENT AND SIGN:
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| 186 | *
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| 187 | * 1) clear leading bit of fraction
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| 188 | * 2) shift and store exponent
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| 189 | */
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| 190 |
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| 191 | *SGL &= SGL_MASK; /* B23-B31 are 0 */
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| 192 | *SGL |= ((long) (f->exp << SGL_EXPSHIFT) << EXP_STORE);
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| 193 | if (f->sign)
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| 194 | *SGL |= CARRYBIT;
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| 195 |
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| 196 | /*
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| 197 | * STORE MANTISSA
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| 198 | */
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| 199 |
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| 200 | put4(*SGL, (char *) &SGL);
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| 201 | }
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| 202 | }
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