99 lines
2.2 KiB
Plaintext
Executable File
99 lines
2.2 KiB
Plaintext
Executable File
/*
|
|
(c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
|
|
See the copyright notice in the ACK home directory, in the file "Copyright".
|
|
*/
|
|
|
|
/* $Header$ */
|
|
|
|
/*
|
|
ROUTINE TO MULTIPLY TWO EXTENDED FORMAT NUMBERS
|
|
*/
|
|
|
|
# include "FP_bias.h"
|
|
# include "FP_trap.h"
|
|
# include "FP_types.h"
|
|
# include "FP_shift.h"
|
|
|
|
void
|
|
mul_ext(e1,e2)
|
|
EXTEND *e1,*e2;
|
|
{
|
|
register int i,j; /* loop control */
|
|
unsigned short mp[4]; /* multiplier */
|
|
unsigned short mc[4]; /* multipcand */
|
|
unsigned short result[8]; /* result */
|
|
register unsigned short *pres;
|
|
|
|
/* first save the sign (XOR) */
|
|
e1->sign ^= e2->sign;
|
|
|
|
/* compute new exponent */
|
|
e1->exp += e2->exp + 1;
|
|
/* 128 bit multiply of mantissas */
|
|
|
|
/* assign unknown long formats */
|
|
/* to known unsigned word formats */
|
|
mp[0] = e1->m1 >> 16;
|
|
mp[1] = (unsigned short) e1->m1;
|
|
mp[2] = e1->m2 >> 16;
|
|
mp[3] = (unsigned short) e1->m2;
|
|
mc[0] = e2->m1 >> 16;
|
|
mc[1] = (unsigned short) e2->m1;
|
|
mc[2] = e2->m2 >> 16;
|
|
mc[3] = (unsigned short) e2->m2;
|
|
for (i = 8; i--;) {
|
|
result[i] = 0;
|
|
}
|
|
/*
|
|
* fill registers with their components
|
|
*/
|
|
for(i=4, pres = &result[4];i--;pres--) if (mp[i]) {
|
|
unsigned short k = 0;
|
|
unsigned long mpi = mp[i];
|
|
for(j=4;j--;) {
|
|
unsigned long tmp = (unsigned long)pres[j] + k;
|
|
if (mc[j]) tmp += mpi * mc[j];
|
|
pres[j] = tmp;
|
|
k = tmp >> 16;
|
|
}
|
|
pres[-1] = k;
|
|
}
|
|
if (! (result[0] & 0x8000)) {
|
|
e1->exp--;
|
|
for (i = 0; i <= 3; i++) {
|
|
result[i] <<= 1;
|
|
if (result[i+1]&0x8000) result[i] |= 1;
|
|
}
|
|
result[4] <<= 1;
|
|
}
|
|
|
|
/*
|
|
* combine the registers to a total
|
|
*/
|
|
e1->m1 = ((unsigned long)(result[0]) << 16) + result[1];
|
|
e1->m2 = ((unsigned long)(result[2]) << 16) + result[3];
|
|
if (result[4] & 0x8000) {
|
|
if (++e1->m2 == 0)
|
|
if (++e1->m1 == 0) {
|
|
e1->m1 = NORMBIT;
|
|
e1->exp++;
|
|
}
|
|
}
|
|
|
|
/* check for overflow */
|
|
if (e1->exp >= EXT_MAX) {
|
|
trap(EFOVFL);
|
|
/* if caught */
|
|
/* return signed infinity */
|
|
e1->exp = EXT_MAX;
|
|
infinity: e1->m1 = e1->m2 =0L;
|
|
return;
|
|
}
|
|
/* check for underflow */
|
|
if (e1->exp < EXT_MIN) {
|
|
trap(EFUNFL);
|
|
e1->exp = EXT_MIN;
|
|
goto infinity;
|
|
}
|
|
}
|