VMAX (floating-point)
Vector Maximum compares corresponding elements in two vectors, and copies the larger of each pair into the corresponding element in the destination vector.
The operand vector elements are floating-point numbers.
Depending on settings in the CPACR, NSACR, and HCPTR registers, and the Security state and PE mode in which the instruction is executed, an attempt to execute the instruction might be undefined, or trapped to Hyp mode. For more information see Enabling Advanced SIMD and floating-point support.
It has encodings from the following instruction sets: A32 ( A1 ) and T32 ( T1 ) .
A1
31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
1 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 0 | D | 0 | sz | Vn | Vd | 1 | 1 | 1 | 1 | N | Q | M | 0 | Vm | |||||||||
op |
if Q == '1' && (Vd<0> == '1' || Vn<0> == '1' || Vm<0> == '1') then UNDEFINED; if sz == '1' && !HaveFP16Ext() then UNDEFINED; maximum = (op == '0'); case sz of when '0' esize = 32; elements = 2; when '1' esize = 16; elements = 4; d = UInt(D:Vd); n = UInt(N:Vn); m = UInt(M:Vm); regs = if Q == '0' then 1 else 2;
T1
15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | D | 0 | sz | Vn | Vd | 1 | 1 | 1 | 1 | N | Q | M | 0 | Vm | |||||||||
op |
if Q == '1' && (Vd<0> == '1' || Vn<0> == '1' || Vm<0> == '1') then UNDEFINED; if sz == '1' && !HaveFP16Ext() then UNDEFINED; if sz == '1' && InITBlock() then UNPREDICTABLE; maximum = (op == '0'); case sz of when '0' esize = 32; elements = 2; when '1' esize = 16; elements = 4; d = UInt(D:Vd); n = UInt(N:Vn); m = UInt(M:Vm); regs = if Q == '0' then 1 else 2;
CONSTRAINED UNPREDICTABLE behavior
If sz == '1' && InITBlock(), then one of the following behaviors must occur:
- The instruction is undefined.
- The instruction executes as if it passes the Condition code check.
- The instruction executes as NOP. This means it behaves as if it fails the Condition code check.
Assembler Symbols
<c> |
For encoding A1: see Standard assembler syntax fields. This encoding must be unconditional. |
For encoding T1: see Standard assembler syntax fields. |
<q> |
<dt> |
Is the data type for the elements of the vectors,
encoded in
sz:
|
<Qd> |
Is the 128-bit name of the SIMD&FP destination register, encoded in the "D:Vd" field as <Qd>*2. |
<Qn> |
Is the 128-bit name of the first SIMD&FP source register, encoded in the "N:Vn" field as <Qn>*2. |
<Qm> |
Is the 128-bit name of the second SIMD&FP source register, encoded in the "M:Vm" field as <Qm>*2. |
<Dd> |
Is the 64-bit name of the SIMD&FP destination register, encoded in the "D:Vd" field. |
<Dn> |
Is the 64-bit name of the first SIMD&FP source register, encoded in the "N:Vn" field. |
<Dm> |
Is the 64-bit name of the second SIMD&FP source register, encoded in the "M:Vm" field. |
Floating-point maximum and minimum
- max(+0.0, -0.0) = +0.0
- If any input is a NaN, the corresponding result element is the default NaN.
Operation
if ConditionPassed() then EncodingSpecificOperations(); CheckAdvSIMDEnabled(); for r = 0 to regs-1 for e = 0 to elements-1 op1 = Elem[D[n+r],e,esize]; op2 = Elem[D[m+r],e,esize]; if maximum then Elem[D[d+r],e,esize] = FPMax(op1, op2, StandardFPSCRValue()); else Elem[D[d+r],e,esize] = FPMin(op1, op2, StandardFPSCRValue());