FCMLT (zero)
Floating-point Compare Less than zero (vector). This instruction reads each floating-point value in the source SIMD&FP register and if the value is less than zero sets every bit of the corresponding vector element in the destination SIMD&FP register to one, otherwise sets every bit of the corresponding vector element in the destination SIMD&FP register to zero.
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.
It has encodings from 4 classes:
Scalar half precision
,
Scalar single-precision and double-precision
,
Vector half precision
and
Vector single-precision and double-precision
Scalar half precision
(Armv8.2)
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 |
0 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 1 | 1 | 0 | 1 | 0 | Rn | Rd |
if !HaveFP16Ext() then UNDEFINED;
integer d = UInt(Rd);
integer n = UInt(Rn);
integer esize = 16;
integer datasize = esize;
integer elements = 1;
CompareOp comparison = CompareOp_LT;
Scalar single-precision and double-precision
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 |
0 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | sz | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 0 | 1 | 0 | Rn | Rd |
integer d = UInt(Rd);
integer n = UInt(Rn);
integer esize = 32 << UInt(sz);
integer datasize = esize;
integer elements = 1;
CompareOp comparison = CompareOp_LT;
Vector half precision
(Armv8.2)
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 |
0 | Q | 0 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 1 | 1 | 0 | 1 | 0 | Rn | Rd |
if !HaveFP16Ext() then UNDEFINED;
integer d = UInt(Rd);
integer n = UInt(Rn);
integer esize = 16;
integer datasize = if Q == '1' then 128 else 64;
integer elements = datasize DIV esize;
CompareOp comparison = CompareOp_LT;
Vector single-precision and double-precision
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 |
0 | Q | 0 | 0 | 1 | 1 | 1 | 0 | 1 | sz | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 0 | 1 | 0 | Rn | Rd |
integer d = UInt(Rd);
integer n = UInt(Rn);
if sz:Q == '10' then UNDEFINED;
integer esize = 32 << UInt(sz);
integer datasize = if Q == '1' then 128 else 64;
integer elements = datasize DIV esize;
CompareOp comparison = CompareOp_LT;
Assembler Symbols
<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 SIMD&FP source register, encoded in the "Rn" field.
|
<V> |
Is a width specifier,
encoded in
sz :
|
<d> |
Is the number of the SIMD&FP destination register, encoded in the "Rd" field.
|
<n> |
Is the number of the SIMD&FP source register, encoded in the "Rn" field.
|
<Vd> |
Is the name of the SIMD&FP destination register, encoded in the "Rd" field.
|
<T> |
For the half-precision variant: is an arrangement specifier,
encoded in
Q :
|
|
For the single-precision and double-precision variant: is an arrangement specifier,
encoded in
sz:Q :
sz |
Q |
<T> |
0 |
0 |
2S |
0 |
1 |
4S |
1 |
0 |
RESERVED |
1 |
1 |
2D |
|
<Vn> |
Is the name of the SIMD&FP source register, encoded in the "Rn" field.
|
Operation
CheckFPAdvSIMDEnabled64();
bits(datasize) operand = V[n];
bits(datasize) result;
bits(esize) zero = FPZero('0');
bits(esize) element;
boolean test_passed;
for e = 0 to elements-1
element = Elem[operand, e, esize];
case comparison of
when CompareOp_GT test_passed = FPCompareGT(element, zero, FPCR);
when CompareOp_GE test_passed = FPCompareGE(element, zero, FPCR);
when CompareOp_EQ test_passed = FPCompareEQ(element, zero, FPCR);
when CompareOp_LE test_passed = FPCompareGE(zero, element, FPCR);
when CompareOp_LT test_passed = FPCompareGT(zero, element, FPCR);
Elem[result, e, esize] = if test_passed then Ones() else Zeros();
V[d] = result;