FMAX (scalar)
Floating-point maximum (scalar)
This instruction compares the two source SIMD&FP registers,
and writes the larger of the two floating-point values to the
destination SIMD&FP register.
When FPCR.AH is 0,
the behavior is as follows:
Negative zero compares less than positive zero.
When FPCR.DN is 0,
if either value is a NaN, the result is a quiet NaN.
When FPCR.DN is 1,
if either value is a NaN, the result is Default NaN.
When FPCR.AH is 1,
the behavior is as follows:
If both values are zeros, regardless of the sign of either
zero, the result is the second value.
If either value is a NaN, regardless of the value of
FPCR.DN, the result is the second value.
This instruction can generate a floating-point exception.
Depending on the settings in FPCR,
the exception results in either a flag being set in FPSR,
or a synchronous exception being generated.
For more information, see
Floating-point exception traps.
Depending on the settings in the CPACR_EL1,
CPTR_EL2, and CPTR_EL3 registers,
and the current Security state and Exception level,
an attempt to execute the instruction might be trapped.
0
0
0
1
1
1
1
0
1
0
1
0
0
1
0
1
1
FMAX <Hd>, <Hn>, <Hm>
0
0
FMAX <Sd>, <Sn>, <Sm>
0
1
FMAX <Dd>, <Dn>, <Dm>
if ftype == '10' || (ftype == '11' && !IsFeatureImplemented(FEAT_FP16)) then UNDEFINED;
constant integer d = UInt(Rd);
constant integer n = UInt(Rn);
constant integer m = UInt(Rm);
constant integer esize = 8 << UInt(ftype EOR '10');
<Hd>
Is the 16-bit name of the SIMD&FP destination register, encoded in the "Rd" field.
<Hn>
Is the 16-bit name of the first SIMD&FP source register, encoded in the "Rn" field.
<Hm>
Is the 16-bit name of the second SIMD&FP source register, encoded in the "Rm" field.
<Sd>
Is the 32-bit name of the SIMD&FP destination register, encoded in the "Rd" field.
<Sn>
Is the 32-bit name of the first SIMD&FP source register, encoded in the "Rn" field.
<Sm>
Is the 32-bit name of the second SIMD&FP source register, encoded in the "Rm" field.
<Dd>
Is the 64-bit name of the SIMD&FP destination register, encoded in the "Rd" field.
<Dn>
Is the 64-bit name of the first SIMD&FP source register, encoded in the "Rn" field.
<Dm>
Is the 64-bit name of the second SIMD&FP source register, encoded in the "Rm" field.
CheckFPEnabled64();
constant bits(esize) operand1 = V[n, esize];
constant bits(esize) operand2 = V[m, esize];
bits(128) result = if IsMerging(FPCR) then V[n, 128] else Zeros(128);
Elem[result, 0, esize] = FPMax(operand1, operand2, FPCR);
V[d, 128] = result;