Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS MANUAL VOLUME 1 REV 2.3 Manual page 989

fnma
fnma — Floating-point Negative Multiply Add
( ) fnma.
Format: qp pc
The product of FR
Description:
is added to this product, again in infinite precision. The resulting value is then rounded
to the precision indicated by pc (and possibly FPSR.sf.pc and FPSR.sf.wre) using the
rounding mode specified by FPSR.sf.rc. The rounded result is placed in FR
If any of FR
result.
If is f0, an IEEE multiply operation is performed, followed by negation of the product.
f
2
See "fnmpy — Floating-point Negative Multiply" on page 3:92.
The mnemonic values for the opcode's pc are given in
mnemonic values for sf are given in
interpretation of the status field's pc, wre, and rc, refer to
page 1:90.
Operation: if (PR[qp]) {
fp_check_target_register(f
if (tmp_isrcode = fp_reg_disabled(f
disabled_fp_register_fault(tmp_isrcode, 0);
if (fp_is_natval(FR[f
fp_is_natval(FR[f
FR[f
fp_update_psr(f
} else {
tmp_default_result = fms_fnma_exception_fault_check(f
if (fp_raise_fault(tmp_fp_env))
if (fp_is_nan_or_inf(tmp_default_result)) {
} else {
}
fp_update_fpsr(sf, tmp_fp_env);
fp_update_psr(f
if (fp_raise_traps(tmp_fp_env))
}
}
Invalid Operation (V)
FP Exceptions:
Denormal/Unnormal Operand (D)
Software Assist (SWA) fault
3:90
. = , ,
sf f f f f
1 3 4 2
and FR is computed to infinite precision, negated, and then FR
f f
3 4
, FR , or FR is a NaTVal, FR
f f f
3 4 2
1
]) || fp_is_natval(FR[f
2
])) {
4
] = NATVAL;
1
);
1
fp_exception_fault(fp_decode_fault(tmp_fp_env));
FR[f ] = tmp_default_result;
1
tmp_res = fp_mul(fp_reg_read(FR[f
tmp_res.sign = !tmp_res.sign;
if (f != 0)
2
tmp_res = fp_add(tmp_res, fp_reg_read(FR[f
FR[f ] = fp_ieee_round(tmp_res, &tmp_fp_env);
1
);
1
fp_exception_trap(fp_decode_trap(tmp_fp_env));
is set to NaTVal instead of the computed
f
1
Table 2-22 on page
Table 2-23 on page 3:56. For the encodings and
);
, f , f , f ))
1 2 3 4
]) ||
3
]), fp_reg_read(FR[f
3
Underflow (U)
Overflow (O)
Inexact (I)
Software Assist (SWA) trap
.
f
1
3:56. The
Table 5-5 and Table 5-6 on
, f , f ,
2 3 4
pc, sf, &tmp_fp_env);
]));
4
]), tmp_fp_env);
2
Volume 3: Instruction Reference
F1
f
2