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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".
- */
- /* $Id$ */
- /*
- SUBTRACT 2 EXTENDED FORMAT NUMBERS
- */
- #include "FP_types.h"
- void
- sub_ext(e1,e2)
- EXTEND *e1,*e2;
- {
- if ((e2->m1 | e2->m2) == 0L) {
- return;
- }
- if ((e1->m1 | e1->m2) == 0L) {
- *e1 = *e2;
- e1->sign = e2->sign ? 0 : 1;
- return;
- }
- sft_ext(e1, e2);
- if (e1->sign != e2->sign) {
- /* e1 - e2 = e1 + (-e2) */
- if (b64_add(&e1->mantissa,&e2->mantissa)) { /* addition carry */
- b64_rsft(&e1->mantissa); /* shift mantissa one bit RIGHT */
- e1->m1 |= 0x80000000L; /* set max bit */
- e1->exp++; /* increase the exponent */
- }
- }
- else if (e2->m1 > e1->m1 ||
- (e2->m1 == e1->m1 && e2->m2 > e1->m2)) {
- /* abs(e2) > abs(e1) */
- if (e1->m2 > e2->m2) {
- e2->m1 -= 1; /* carry in */
- }
- e2->m1 -= e1->m1;
- e2->m2 -= e1->m2;
- *e1 = *e2;
- e1->sign = e2->sign ? 0 : 1;
- }
- else {
- if (e2->m2 > e1->m2)
- e1->m1 -= 1; /* carry in */
- e1->m1 -= e2->m1;
- e1->m2 -= e2->m2;
- }
- nrm_ext(e1);
- }
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