FCVTZS (scalar, fixed-point)

Floating-point Convert to Signed fixed-point, rounding toward Zero (scalar). This instruction converts the floating-point value in the SIMD&FP source register to a 32-bit or 64-bit fixed-point signed 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.

313029282726252423222120191817161514131211109876543210
sf0011110ftype011000scaleRnRd
Srmodeopcode

Half-precision to 32-bit (sf == 0 && ftype == 11)
(FEAT_FP16)

FCVTZS <Wd>, <Hn>, #<fbits>

Half-precision to 64-bit (sf == 1 && ftype == 11)
(FEAT_FP16)

FCVTZS <Xd>, <Hn>, #<fbits>

Single-precision to 32-bit (sf == 0 && ftype == 00)

FCVTZS <Wd>, <Sn>, #<fbits>

Single-precision to 64-bit (sf == 1 && ftype == 00)

FCVTZS <Xd>, <Sn>, #<fbits>

Double-precision to 32-bit (sf == 0 && ftype == 01)

FCVTZS <Wd>, <Dn>, #<fbits>

Double-precision to 64-bit (sf == 1 && ftype == 01)

FCVTZS <Xd>, <Dn>, #<fbits>

if ftype == '10' || (ftype == '11' && !IsFeatureImplemented(FEAT_FP16)) then UNDEFINED; if sf == '0' && scale<5> == '0' then UNDEFINED; integer d = UInt(Rd); integer n = UInt(Rn); constant integer intsize = 32 << UInt(sf); constant integer decode_fltsize = 8 << UInt(ftype EOR '10'); integer fracbits = 64 - UInt(scale); FPRounding rounding = FPRounding_ZERO; boolean unsigned = FALSE;

Assembler Symbols

<Wd>

Is the 32-bit name of the general-purpose destination register, encoded in the "Rd" field.

<Hn>

Is the 16-bit name of the SIMD&FP source register, encoded in the "Rn" field.

<fbits>

For the double-precision to 32-bit, half-precision to 32-bit and single-precision to 32-bit variant: is the number of bits after the binary point in the fixed-point destination, in the range 1 to 32, encoded as 64 minus "scale".

For the double-precision to 64-bit, half-precision to 64-bit and single-precision to 64-bit variant: is the number of bits after the binary point in the fixed-point destination, in the range 1 to 64, encoded as 64 minus "scale".

<Xd>

Is the 64-bit name of the general-purpose destination register, encoded in the "Rd" field.

<Sn>

Is the 32-bit name of the SIMD&FP source register, encoded in the "Rn" field.

<Dn>

Is the 64-bit name of the SIMD&FP source register, encoded in the "Rn" field.

Operation

CheckFPEnabled64(); bits(decode_fltsize) fltval = V[n, decode_fltsize]; X[d, intsize] = FPToFixed(fltval, fracbits, unsigned, FPCR, rounding, intsize);

Operational information

If FEAT_SME is implemented and the PE is in Streaming SVE mode, then any subsequent instruction which is dependent on the general-purpose register written by this instruction might be significantly delayed.


Internal version only: aarchmrs v2024-03_relA, pseudocode v2024-03_rel, sve v2024-03_rel ; Build timestamp: 2024-03-26T09:45

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