FCVTZU (vector, fixed-point)

Floating-point Convert to Unsigned fixed-point, rounding toward Zero (vector). This instruction converts a scalar or each element in a vector from floating-point to fixed-point unsigned integer using the Round towards Zero 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 Security state and Exception level in which the instruction is executed, an attempt to execute the instruction might be trapped.

It has encodings from 2 classes: Scalar and Vector

Scalar

313029282726252423222120191817161514131211109876543210
011111110!= 0000immb111111RnRd
Uimmhopcode

FCVTZU <V><d>, <V><n>, #<fbits>

integer d = UInt(Rd); integer n = UInt(Rn); if immh IN {'000x'} || (immh IN {'001x'} && !IsFeatureImplemented(FEAT_FP16)) then UNDEFINED; constant integer esize = if immh IN {'1xxx'} then 64 else if immh IN {'01xx'} then 32 else 16; constant integer datasize = esize; integer elements = 1; integer fracbits = (esize * 2) - UInt(immh:immb); boolean unsigned = (U == '1'); FPRounding rounding = FPRounding_ZERO;

Vector

313029282726252423222120191817161514131211109876543210
0Q1011110!= 0000immb111111RnRd
Uimmhopcode

FCVTZU <Vd>.<T>, <Vn>.<T>, #<fbits>

integer d = UInt(Rd); integer n = UInt(Rn); if immh == '0000' then SEE(asimdimm); if immh IN {'000x'} || (immh IN {'001x'} && !IsFeatureImplemented(FEAT_FP16)) then UNDEFINED; if immh<3>:Q == '10' then UNDEFINED; constant integer esize = if immh IN {'1xxx'} then 64 else if immh IN {'01xx'} then 32 else 16; constant integer datasize = 64 << UInt(Q); integer elements = datasize DIV esize; integer fracbits = (esize * 2) - UInt(immh:immb); boolean unsigned = (U == '1'); FPRounding rounding = FPRounding_ZERO;

Assembler Symbols

<V>

Is a width specifier, encoded in immh:

immh <V>
0001 RESERVED
001x H
01xx S
1xxx D
<d>

Is the number of the SIMD&FP destination register, in the "Rd" field.

<n>

Is the number of the first SIMD&FP source register, encoded in the "Rn" field.

<fbits>

For the scalar variant: is the number of fractional bits, in the range 1 to the operand width, encoded in immh:immb:

immh <fbits>
0001 RESERVED
001x 32 - UInt(immh:immb)
01xx 64 - UInt(immh:immb)
1xxx 128 - UInt(immh:immb)

For the vector variant: is the number of fractional bits, in the range 1 to the element width, encoded in immh:immb:

immh <fbits>
0001 RESERVED
001x 32 - UInt(immh:immb)
01xx 64 - UInt(immh:immb)
1xxx 128 - UInt(immh:immb)
<Vd>

Is the name of the SIMD&FP destination register, encoded in the "Rd" field.

<T>

Is an arrangement specifier, encoded in immh:Q:

immh Q <T>
0001 x RESERVED
001x 0 4H
001x 1 8H
01xx 0 2S
01xx 1 4S
1xxx 0 RESERVED
1xxx 1 2D
<Vn>

Is the name of the SIMD&FP source register, encoded in the "Rn" field.

Operation

CheckFPAdvSIMDEnabled64(); bits(datasize) operand = V[n, datasize]; bits(esize) element; boolean merge = elements == 1 && IsMerging(FPCR); bits(128) result = if merge then V[d, 128] else Zeros(128); for e = 0 to elements-1 element = Elem[operand, e, esize]; Elem[result, e, esize] = FPToFixed(element, fracbits, unsigned, FPCR, rounding, esize); V[d, 128] = result;


Internal version only: aarchmrs v2023-12_rel, pseudocode v2023-12_rel, sve v2023-12_rel ; Build timestamp: 2023-12-15T16:46

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