FCVTAS (scalar SIMD&FP)

Floating-point convert to signed integer, rounding to nearest with ties to away (scalar SIMD&FP)

This instruction converts the floating-point value in the SIMD&FP source register to a 32-bit or 64-bit signed integer using the Round to Nearest with Ties to Away rounding mode, and writes the result to the SIMD&FP destination register.

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 exceptions and 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.

Floating-point
(FEAT_FPRCVT)

313029282726252423222120191817161514131211109876543210
sf0011110ftype111010000000RnRd
Srmodeopcode

Encoding for the Half-precision to 32-bit variant

Applies when (sf == 0 && ftype == 11)

FCVTAS <Sd>, <Hn>

Encoding for the Half-precision to 64-bit variant

Applies when (sf == 1 && ftype == 11)

FCVTAS <Dd>, <Hn>

Encoding for the Single-precision to 64-bit variant

Applies when (sf == 1 && ftype == 00)

FCVTAS <Dd>, <Sn>

Encoding for the Double-precision to 32-bit variant

Applies when (sf == 0 && ftype == 01)

FCVTAS <Sd>, <Dn>

Decode for all variants of this encoding

if !IsFeatureImplemented(FEAT_FPRCVT) then EndOfDecode(Decode_UNDEF); end; let d : integer = UInt(Rd); let n : integer = UInt(Rn); let intsize : integer{} = 32 << UInt(sf); let fltsize : integer{} = 8 << UInt(ftype XOR '10');

Assembler Symbols

<Sd>

Is the 32-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.

<Dd>

Is the 64-bit name of the SIMD&FP 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

AArch64_CheckFPEnabled(); var fltval : bits(fltsize); var intval : bits(intsize); let merge : boolean = IsMerging(FPCR()); var result : bits(128) = if merge then V{128}(d) else Zeros{128}; fltval = V{fltsize}(n); intval = FPToFixed{intsize, fltsize}(fltval, 0, FALSE, FPCR(), FPRounding_TIEAWAY); result[0+:intsize] = intval; V{128}(d) = result;


2026-03_rel 2026-03-26 20:48:11

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