FRINTN (vector)

Floating-point Round to Integral, to nearest with ties to even (vector). This instruction rounds a vector of floating-point values in the SIMD&FP source register to integral floating-point values of the same size using the Round to Nearest rounding mode, and writes the result to the SIMD&FP destination register.

A zero input gives a zero result with the same sign, an infinite input gives an infinite result with the same sign, and a NaN is propagated as for normal arithmetic.

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.

It has encodings from 2 classes: Half-precision and Single-precision and double-precision

Half-precision
(FEAT_FP16)

313029282726252423222120191817161514131211109876543210
0Q00111001111001100010RnRd
Uo2o1

FRINTN <Vd>.<T>, <Vn>.<T>

if !IsFeatureImplemented(FEAT_FP16) then UNDEFINED; integer d = UInt(Rd); integer n = UInt(Rn); constant integer esize = 16; constant integer datasize = 64 << UInt(Q); integer elements = datasize DIV esize; boolean exact = FALSE; FPRounding rounding; case U:o1:o2 of when '0xx' rounding = FPDecodeRounding(o1:o2); when '100' rounding = FPRounding_TIEAWAY; when '101' UNDEFINED; when '110' rounding = FPRoundingMode(FPCR); exact = TRUE; when '111' rounding = FPRoundingMode(FPCR);

Single-precision and double-precision

313029282726252423222120191817161514131211109876543210
0Q0011100sz100001100010RnRd
Uo2o1

FRINTN <Vd>.<T>, <Vn>.<T>

integer d = UInt(Rd); integer n = UInt(Rn); if sz:Q == '10' then UNDEFINED; constant integer esize = 32 << UInt(sz); constant integer datasize = 64 << UInt(Q); integer elements = datasize DIV esize; boolean exact = FALSE; FPRounding rounding; case U:o1:o2 of when '0xx' rounding = FPDecodeRounding(o1:o2); when '100' rounding = FPRounding_TIEAWAY; when '101' UNDEFINED; when '110' rounding = FPRoundingMode(FPCR); exact = TRUE; when '111' rounding = FPRoundingMode(FPCR);

Assembler Symbols

<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:

Q <T>
0 4H
1 8H

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, datasize]; bits(datasize) result; bits(esize) element; for e = 0 to elements-1 element = Elem[operand, e, esize]; Elem[result, e, esize] = FPRoundInt(element, FPCR, rounding, exact); V[d, datasize] = result;


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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