fcvtmu

Floating-Point Convert to Unsigned Integer (Minus Infinity)

FCVTMU <Wd|Xd>, <Hn|Sn|Dn>

Converts float to unsigned integer, rounding towards minus infinity.

Details

Converts a scalar floating-point value to an unsigned integer, rounding towards negative infinity (floor). Sets condition flags based on the integer result. Raises Invalid Operation exception on overflow or invalid input. AArch64-only instruction.

Pseudocode Operation

operand ← Vn
intval ← Floor(operand)
if intval > MaxUInt(destination_width) or intval < 0 then
  GenerateException(InvalidOperation)
else
  Rd ← ZeroExtend(intval)
  UpdateFlags(intval)
end

Example

FCVTMU Wd, Dn

Encoding

Binary Layout
0
0
0
11110
00
1
10
001
000000
Rn
Rd
 
Format FP Conversion
Opcode 0x1E310000
Extension Floating Point

Operands

  • Rd
    Int Dest
  • Vn
    Float Src

Reference (Arm A64 ISA)

Instruction Forms

Encoding Instruction ISA Bit pattern
0x7E79B800 FCVTMU <Hd>, <Hn> A64 01 | 1 | 11110 | 0 | 1111001101 | 1 | 10 | Rn | Rd
0x7E21B800 FCVTMU <V><d>, <V><n> A64 01 | 1 | 11110 | 0 | sz | 100001101 | 1 | 10 | Rn | Rd
0x2E79B800 FCVTMU <Vd>.<T>, <Vn>.<T> A64 0 | Q | 1 | 01110 | 0 | 1111001101 | 1 | 10 | Rn | Rd
0x2E21B800 FCVTMU <Vd>.<T>, <Vn>.<T> A64 0 | Q | 1 | 01110 | 0 | sz | 100001101 | 1 | 10 | Rn | Rd
0x1EF10000 FCVTMU <Wd>, <Hn> A64 0 | 0 | 0 | 11110 | 11 | 1 | 10 | 001 | 000000 | Rn | Rd
0x9EF10000 FCVTMU <Xd>, <Hn> A64 1 | 0 | 0 | 11110 | 11 | 1 | 10 | 001 | 000000 | Rn | Rd
0x1E310000 FCVTMU <Wd>, <Sn> A64 0 | 0 | 0 | 11110 | 00 | 1 | 10 | 001 | 000000 | Rn | Rd
0x9E310000 FCVTMU <Xd>, <Sn> A64 1 | 0 | 0 | 11110 | 00 | 1 | 10 | 001 | 000000 | Rn | Rd
0x1E710000 FCVTMU <Wd>, <Dn> A64 0 | 0 | 0 | 11110 | 01 | 1 | 10 | 001 | 000000 | Rn | Rd
0x9E710000 FCVTMU <Xd>, <Dn> A64 1 | 0 | 0 | 11110 | 01 | 1 | 10 | 001 | 000000 | Rn | Rd

Description

Floating-point Convert to Unsigned integer, rounding toward Minus infinity (scalar). This instruction converts the floating-point value in the SIMD&FP source register to a 32-bit or 64-bit unsigned integer using the Round towards Minus Infinity rounding mode, and writes the result to the general-purpose destination register. A floating-point exception can be generated by this instruction. 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.

Operation

CheckFPEnabled64();

bits(decode_fltsize) fltval;
bits(intsize) intval;

fltval = V[n, decode_fltsize];
intval = FPToFixed(fltval, 0, TRUE, FPCR, rounding, intsize);
X[d, intsize] = intval;