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- /*
- (c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
- See the copyright notice in the ACK home directory, in the file "Copyright".
- */
- /* $Id$ */
- /*
- CONVERTS FLOATING POINT TO EXTENDED FORMAT
- Two sizes of FLOATING Point are known:
- SINGLE and DOUBLE
- */
- /********************************************************/
- /*
- It is not required to normalize in extended
- format, but it has been chosen to do so.
- Extended Format is as follows (at exit):
- ->sign S000 0000 | 0000 0000 <SIGN>
- ->exp 0EEE EEEE | EEEE EEEE <EXPONENT>
- ->m1 LFFF FFFF | FFFF FFFF <L.Fraction>
- FFFF FFFF | FFFF FFFF <Fraction>
- ->m2 FFFF FFFF | FFFF FFFF <Fraction>
- FFFF F000 | 0000 0000 <Fraction>
- */
- /********************************************************/
- #include "FP_bias.h"
- #include "FP_shift.h"
- #include "FP_types.h"
- #include "get_put.h"
- /********************************************************/
- void
- extend(from,to,size)
- unsigned long *from;
- EXTEND *to;
- int size;
- {
- register char *cpt1;
- unsigned long tmp;
- int leadbit = 0;
- cpt1 = (char *) from;
- #if FL_MSL_AT_LOW_ADDRESS
- #if FL_MSW_AT_LOW_ADDRESS
- to->exp = uget2(cpt1);
- #else
- to->exp = uget2(cpt1+2);
- #endif
- #else
- #if FL_MSW_AT_LOW_ADDRESS
- to->exp = uget2(cpt1+(size == sizeof(DOUBLE) ? 4 : 0));
- #else
- to->exp = uget2(cpt1+(size == sizeof(DOUBLE) ? 6 : 2));
- #endif
- #endif
- to->sign = (to->exp & 0x8000); /* set sign bit */
- to->exp ^= to->sign;
- if (size == sizeof(DOUBLE))
- to->exp >>= DBL_EXPSHIFT;
- else
- to->exp >>= SGL_EXPSHIFT;
- if (to->exp > 0)
- leadbit++; /* will set Lead bit later */
- else to->exp++;
- if (size == sizeof(DOUBLE)) {
- #if FL_MSL_AT_LOW_ADDRESS
- to->m1 = get4(cpt1);
- cpt1 += 4;
- tmp = get4(cpt1);
- #else
- tmp = get4(cpt1);
- cpt1 += 4;
- to->m1 = get4(cpt1);
- #endif
- if (to->exp == 1 && to->m1 == 0 && tmp == 0) {
- to->exp = 0;
- to->sign = 0;
- to->m1 = 0;
- to->m2 = 0;
- return;
- }
- to->m1 <<= DBL_M1LEFT; /* shift */
- to->exp -= DBL_BIAS; /* remove bias */
- to->m1 |= (tmp>>DBL_RPACK); /* plus 10 == 32 */
- to->m2 = (tmp<<DBL_LPACK); /* plus 22 == 32 */
- }
- else { /* size == sizeof(SINGLE) */
- to->m1 = get4(cpt1);
- to->m1 <<= SGL_M1LEFT; /* shift */
- if (to->exp == 1 && to->m1 == 0) {
- to->exp = 0;
- to->sign = 0;
- to->m1 = 0;
- to->m2 = 0;
- return;
- }
- to->exp -= SGL_BIAS; /* remove bias */
- to->m2 = 0L;
- }
- to->m1 |= NORMBIT; /* set bit L */
- if (leadbit == 0) { /* set or clear Leading Bit */
- to->m1 &= ~NORMBIT; /* clear bit L */
- nrm_ext(to); /* and normalize */
- }
- }
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