Intel Itanium 9150M, Manual, Page: 125 / 420

3:116 Volume 3: Instruction Reference
fpms
fpms — Floating-point Parallel Multiply Subtract
Format: (
qp
) fpms.
sf f
1
=
f
3
,
f
4
,
f
2
F1
Description:
The pair of products of the pairs of single precision values in the significand fields of FR
f
3
and FR
f
4
are computed to infinite precision and then the pair of single precision
values in the significand field of FR
f
2
is subtracted from these products, again in infinite
precision. The resulting values are then rounded to single precision using the rounding
mode specified by FPSR.
sf . rc . The pair of rounded results are stored in the significand
field of FR
f
1
. The exponent field of FR
f
1
is set to the biased exponent for 2.0
63
(0x1003E) and the sign field of FR
f
1
is set to positive (0).
Note: If any of FR
f
3
, FR
f
4
, or FR
f
2
is a NaTVal, FR
f
1
is set to NaTVal instead of the
computed results.
Mapping:
If
f
2
is f0 in the fpms instruction, just the IEEE multiply operation is performed.
The mnemonic values for
sf
are given in Table 2-23 on page 3:56 .
The encodings and interpretation for the status field’s rc are given in Table 5-6 on
page 1:90 .
Operation: if (PR[ qp ]) {
fp_check_target_register( f
1
);
if (tmp_isrcode = fp_reg_disabled( f
1
, f
2
, f
3
, f
4
))
disabled_fp_register_fault(tmp_isrcode, 0);
if (fp_is_natval(FR[ f
2
]) || fp_is_natval(FR[ f
3
]) ||
fp_is_natval(FR[ f
4
])) {
FR[ f
1
] = NATVAL;
fp_update_psr( f
1
);
} else {
tmp_default_result_pair = fpms_fpnma_exception_fault_check( f
2
, f
3
,
f
4
, sf, &tmp_fp_env);
if (fp_raise_fault(tmp_fp_env))
fp_exception_fault(fp_decode_fault(tmp_fp_env));
if (fp_is_nan_or_inf(tmp_default_result_pair.hi)) {
tmp_res_hi = fp_single(tmp_default_result_pair.hi);
} else {
tmp_res = fp_mul(fp_reg_read_hi( f
3
), fp_reg_read_hi( f
4
));
if ( f
2
!= 0) {
tmp_sub = fp_reg_read_hi( f
2
);
tmp_sub.sign = !tmp_sub.sign;
tmp_res = fp_add(tmp_res, tmp_sub, tmp_fp_env);
}
tmp_res_hi = fp_ieee_round_sp(tmp_res, HIGH, &tmp_fp_env);
}
if (fp_is_nan_or_inf(tmp_default_result_pair.lo)) {
tmp_res_lo = fp_single(tmp_default_result_pair.lo);
} else {
tmp_res = fp_mul(fp_reg_read_lo( f
3
), fp_reg_read_lo( f
4
));
if ( f
2
!= 0) {
tmp_sub = fp_reg_read_lo( f
2
);
tmp_sub.sign = !tmp_sub.sign;
tmp_res = fp_add(tmp_res, tmp_sub, tmp_fp_env);
}