static float32 propagateFloat32NaN( float32 a, float32 b )
{
flag aIsNaN, aIsSignalingNaN, bIsNaN, bIsSignalingNaN;
aIsNaN = float32_is_nan( a );
aIsSignalingNaN = float32_is_signaling_nan( a );
bIsNaN = float32_is_nan( b );
bIsSignalingNaN = float32_is_signaling_nan( b );
a |= 0x00400000;
b |= 0x00400000;
if ( aIsSignalingNaN | bIsSignalingNaN ) float_raise( float_flag_invalid );
if ( aIsSignalingNaN ) {
if ( bIsSignalingNaN ) goto returnLargerSignificand;
return bIsNaN ? b : a;
}
else if ( aIsNaN ) {
if ( bIsSignalingNaN | ! bIsNaN ) return a;
returnLargerSignificand:
if ( (bits32) ( a<<1 ) < (bits32) ( b<<1 ) ) return b;
if ( (bits32) ( b<<1 ) < (bits32) ( a<<1 ) ) return a;
return ( a < b ) ? a : b;
}
else {
return b;
}
}
BX_INSF_TYPE BX_CPP_AttrRegparmN(1) BX_CPU_C::FCOM_SINGLE_REAL(bxInstruction_c *i)
{
BX_CPU_THIS_PTR prepareFPU(i);
int pop_stack = i->nnn() & 1, rc;
RMAddr(i) = BX_CPU_CALL_METHODR(i->ResolveModrm, (i));
float32 load_reg = read_virtual_dword(i->seg(), RMAddr(i));
BX_CPU_THIS_PTR FPU_update_last_instruction(i);
clear_C1();
if (IS_TAG_EMPTY(0))
{
FPU_exception(FPU_EX_Stack_Underflow);
setcc(FPU_SW_C0|FPU_SW_C2|FPU_SW_C3);
if(BX_CPU_THIS_PTR the_i387.is_IA_masked())
{
if (pop_stack)
BX_CPU_THIS_PTR the_i387.FPU_pop();
}
BX_NEXT_INSTR(i);
}
float_status_t status =
FPU_pre_exception_handling(BX_CPU_THIS_PTR the_i387.get_control_word());
floatx80 a = BX_READ_FPU_REG(0);
if (floatx80_is_nan(a) || floatx80_is_unsupported(a) || float32_is_nan(load_reg)) {
rc = float_relation_unordered;
float_raise(status, float_flag_invalid);
}
else {
rc = floatx80_compare(a, float32_to_floatx80(load_reg, status), status);
}
setcc(status_word_flags_fpu_compare(rc));
if (! FPU_exception(status.float_exception_flags)) {
if (pop_stack)
BX_CPU_THIS_PTR the_i387.FPU_pop();
}
BX_NEXT_INSTR(i);
}
/* This instruction sets the flags N, Z, C, V in the FPSR. */
static unsigned int PerformComparison(const unsigned int opcode)
{
FPA11 *fpa11 = GET_FPA11();
unsigned int Fn = getFn(opcode), Fm = getFm(opcode);
int e_flag = opcode & 0x400000; /* 1 if CxFE */
int n_flag = opcode & 0x200000; /* 1 if CNxx */
unsigned int flags = 0;
#ifdef CONFIG_FPE_NWFPE_XP
floatx80 rFn, rFm;
/* Check for unordered condition and convert all operands to 80-bit
format.
?? Might be some mileage in avoiding this conversion if possible.
Eg, if both operands are 32-bit, detect this and do a 32-bit
comparison (cheaper than an 80-bit one). */
switch (fpa11->fType[Fn]) {
case typeSingle:
//printk("single.\n");
if (float32_is_nan(fpa11->fpreg[Fn].fSingle))
goto unordered;
rFn = float32_to_floatx80(fpa11->fpreg[Fn].fSingle);
break;
case typeDouble:
//printk("double.\n");
if (float64_is_nan(fpa11->fpreg[Fn].fDouble))
goto unordered;
rFn = float64_to_floatx80(fpa11->fpreg[Fn].fDouble);
break;
case typeExtended:
//printk("extended.\n");
if (floatx80_is_nan(fpa11->fpreg[Fn].fExtended))
goto unordered;
rFn = fpa11->fpreg[Fn].fExtended;
break;
default:
return 0;
}
if (CONSTANT_FM(opcode)) {
//printk("Fm is a constant: #%d.\n",Fm);
rFm = getExtendedConstant(Fm);
if (floatx80_is_nan(rFm))
goto unordered;
} else {
//printk("Fm = r%d which contains a ",Fm);
switch (fpa11->fType[Fm]) {
case typeSingle:
//printk("single.\n");
if (float32_is_nan(fpa11->fpreg[Fm].fSingle))
goto unordered;
rFm = float32_to_floatx80(fpa11->fpreg[Fm].fSingle);
break;
case typeDouble:
//printk("double.\n");
if (float64_is_nan(fpa11->fpreg[Fm].fDouble))
goto unordered;
rFm = float64_to_floatx80(fpa11->fpreg[Fm].fDouble);
break;
case typeExtended:
//printk("extended.\n");
if (floatx80_is_nan(fpa11->fpreg[Fm].fExtended))
goto unordered;
rFm = fpa11->fpreg[Fm].fExtended;
break;
default:
return 0;
}
}
if (n_flag)
rFm.high ^= 0x8000;
/* test for less than condition */
if (floatx80_lt(rFn, rFm))
flags |= CC_NEGATIVE;
/* test for equal condition */
if (floatx80_eq(rFn, rFm))
flags |= CC_ZERO;
/* test for greater than or equal condition */
if (floatx80_lt(rFm, rFn))
flags |= CC_CARRY;
#else
if (CONSTANT_FM(opcode)) {
/* Fm is a constant. Do the comparison in whatever precision
Fn happens to be stored in. */
if (fpa11->fType[Fn] == typeSingle) {
float32 rFm = getSingleConstant(Fm);
float32 rFn = fpa11->fpreg[Fn].fSingle;
if (float32_is_nan(rFn))
goto unordered;
if (n_flag)
rFm ^= 0x80000000;
/* test for less than condition */
if (float32_lt_nocheck(rFn, rFm))
flags |= CC_NEGATIVE;
/* test for equal condition */
if (float32_eq_nocheck(rFn, rFm))
flags |= CC_ZERO;
/* test for greater than or equal condition */
if (float32_lt_nocheck(rFm, rFn))
flags |= CC_CARRY;
} else {
float64 rFm = getDoubleConstant(Fm);
float64 rFn = fpa11->fpreg[Fn].fDouble;
if (float64_is_nan(rFn))
goto unordered;
if (n_flag)
rFm ^= 0x8000000000000000ULL;
/* test for less than condition */
if (float64_lt_nocheck(rFn, rFm))
flags |= CC_NEGATIVE;
/* test for equal condition */
if (float64_eq_nocheck(rFn, rFm))
flags |= CC_ZERO;
/* test for greater than or equal condition */
if (float64_lt_nocheck(rFm, rFn))
flags |= CC_CARRY;
}
} else {
/* Both operands are in registers. */
if (fpa11->fType[Fn] == typeSingle
&& fpa11->fType[Fm] == typeSingle) {
float32 rFm = fpa11->fpreg[Fm].fSingle;
float32 rFn = fpa11->fpreg[Fn].fSingle;
if (float32_is_nan(rFn)
|| float32_is_nan(rFm))
goto unordered;
if (n_flag)
rFm ^= 0x80000000;
/* test for less than condition */
if (float32_lt_nocheck(rFn, rFm))
flags |= CC_NEGATIVE;
/* test for equal condition */
if (float32_eq_nocheck(rFn, rFm))
flags |= CC_ZERO;
/* test for greater than or equal condition */
if (float32_lt_nocheck(rFm, rFn))
flags |= CC_CARRY;
} else {
/* Promote 32-bit operand to 64 bits. */
float64 rFm, rFn;
rFm = (fpa11->fType[Fm] == typeSingle) ?
float32_to_float64(fpa11->fpreg[Fm].fSingle)
: fpa11->fpreg[Fm].fDouble;
rFn = (fpa11->fType[Fn] == typeSingle) ?
float32_to_float64(fpa11->fpreg[Fn].fSingle)
: fpa11->fpreg[Fn].fDouble;
if (float64_is_nan(rFn)
|| float64_is_nan(rFm))
goto unordered;
if (n_flag)
rFm ^= 0x8000000000000000ULL;
/* test for less than condition */
if (float64_lt_nocheck(rFn, rFm))
flags |= CC_NEGATIVE;
/* test for equal condition */
if (float64_eq_nocheck(rFn, rFm))
flags |= CC_ZERO;
/* test for greater than or equal condition */
if (float64_lt_nocheck(rFm, rFn))
flags |= CC_CARRY;
}
}
#endif
writeConditionCodes(flags);
return 1;
unordered:
/* ?? The FPA data sheet is pretty vague about this, in particular
about whether the non-E comparisons can ever raise exceptions.
This implementation is based on a combination of what it says in
the data sheet, observation of how the Acorn emulator actually
behaves (and how programs expect it to) and guesswork. */
flags |= CC_OVERFLOW;
flags &= ~(CC_ZERO | CC_NEGATIVE);
if (BIT_AC & readFPSR())
flags |= CC_CARRY;
if (e_flag)
float_raise(float_flag_invalid);
writeConditionCodes(flags);
return 1;
}