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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".
- */
- /* $Id$ */
- #include "flt_misc.h"
- void
- flt_add(e1,e2,e3)
- register flt_arith *e1,*e2,*e3;
- {
- /* Add two extended numbers e1 and e2, and put the result
- in e3
- */
- flt_arith ce1, ce2;
- int diff;
- flt_status = 0;
- if ((e2->m1 | e2->m2) == 0L) {
- *e3 = *e1;
- return;
- }
- if ((e1->m1 | e1->m2) == 0L) {
- *e3 = *e2;
- return;
- }
- ce2 = *e2;
- ce1 = *e1;
- e1 = &ce1;
- e2 = &ce2;
- /* adjust mantissas to equal power */
- diff = e2->flt_exp - e1->flt_exp;
- if (diff < 0) {
- diff = -diff;
- e2->flt_exp += diff;
- flt_b64_sft(&(e2->flt_mantissa), diff);
- }
- else if (diff > 0) {
- e1->flt_exp += diff;
- flt_b64_sft(&(e1->flt_mantissa), diff);
- }
- if (e1->flt_sign != e2->flt_sign) {
- /* e2 + e1 = e2 - (-e1) */
- int tmp = ucmp(e1->m1, e2->m1);
- int tmp2 = ucmp(e1->m2, e2->m2);
- if (tmp > 0 || (tmp == 0 && tmp2 > 0)) {
- /* abs(e1) > abs(e2) */
- if (tmp2 < 0) {
- e1->m1 -= 1; /* carry in */
- }
- e1->m1 -= e2->m1;
- e1->m2 -= e2->m2;
- *e3 = *e1;
- }
- else {
- if (tmp2 > 0)
- e2->m1 -= 1; /* carry in */
- e2->m1 -= e1->m1;
- e2->m2 -= e1->m2;
- *e3 = *e2;
- }
- }
- else {
- *e3 = *e2;
- if (flt_b64_add(&e3->flt_mantissa,&e1->flt_mantissa)) {/* addition carry */
- flt_b64_sft(&e3->flt_mantissa, 1);
- e3->m1 |= 0x80000000L; /* set max bit */
- e3->flt_exp++; /* increase the exponent */
- }
- }
- flt_nrm(e3);
- flt_chk(e3);
- }
- void
- flt_sub(e1,e2,e3)
- flt_arith *e1,*e2,*e3;
- {
- e2->flt_sign = ! e2->flt_sign;
- flt_add(e1,e2,e3);
- e2->flt_sign = ! e2->flt_sign;
- }
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