FCVT

Floating-point convert precision (predicated)

Convert the size and precision of each active floating-point element of the source vector, and place the results in the corresponding elements of the destination vector. Inactive elements in the destination vector register remain unmodified.

Since the input and result types have a different size the smaller type is held unpacked in the least significant bits of elements of the larger size. When the input is the smaller type the upper bits of each source element are ignored. When the result is the smaller type the results are zero-extended to fill each destination element.

It has encodings from 6 classes: Half-precision to single-precision , Half-precision to double-precision , Single-precision to half-precision , Single-precision to double-precision , Double-precision to half-precision and Double-precision to single-precision

Half-precision to single-precision

313029282726252423222120191817161514131211109876543210
0110010110001001101PgZnZd

FCVT <Zd>.S, <Pg>/M, <Zn>.H

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; constant integer esize = 32; constant integer g = UInt(Pg); constant integer n = UInt(Zn); constant integer d = UInt(Zd); constant integer s_esize = 16; constant integer d_esize = 32;

Half-precision to double-precision

313029282726252423222120191817161514131211109876543210
0110010111001001101PgZnZd

FCVT <Zd>.D, <Pg>/M, <Zn>.H

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; constant integer esize = 64; constant integer g = UInt(Pg); constant integer n = UInt(Zn); constant integer d = UInt(Zd); constant integer s_esize = 16; constant integer d_esize = 64;

Single-precision to half-precision

313029282726252423222120191817161514131211109876543210
0110010110001000101PgZnZd

FCVT <Zd>.H, <Pg>/M, <Zn>.S

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; constant integer esize = 32; constant integer g = UInt(Pg); constant integer n = UInt(Zn); constant integer d = UInt(Zd); constant integer s_esize = 32; constant integer d_esize = 16;

Single-precision to double-precision

313029282726252423222120191817161514131211109876543210
0110010111001011101PgZnZd

FCVT <Zd>.D, <Pg>/M, <Zn>.S

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; constant integer esize = 64; constant integer g = UInt(Pg); constant integer n = UInt(Zn); constant integer d = UInt(Zd); constant integer s_esize = 32; constant integer d_esize = 64;

Double-precision to half-precision

313029282726252423222120191817161514131211109876543210
0110010111001000101PgZnZd

FCVT <Zd>.H, <Pg>/M, <Zn>.D

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; constant integer esize = 64; constant integer g = UInt(Pg); constant integer n = UInt(Zn); constant integer d = UInt(Zd); constant integer s_esize = 64; constant integer d_esize = 16;

Double-precision to single-precision

313029282726252423222120191817161514131211109876543210
0110010111001010101PgZnZd

FCVT <Zd>.S, <Pg>/M, <Zn>.D

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; constant integer esize = 64; constant integer g = UInt(Pg); constant integer n = UInt(Zn); constant integer d = UInt(Zd); constant integer s_esize = 64; constant integer d_esize = 32;

Assembler Symbols

<Zd>

Is the name of the destination scalable vector register, encoded in the "Zd" field.

<Pg>

Is the name of the governing scalable predicate register P0-P7, encoded in the "Pg" field.

<Zn>

Is the name of the source scalable vector register, encoded in the "Zn" field.

Operation

CheckSVEEnabled(); constant integer VL = CurrentVL; constant integer PL = VL DIV 8; constant integer elements = VL DIV esize; constant bits(PL) mask = P[g, PL]; constant bits(VL) operand = if AnyActiveElement(mask, esize) then Z[n, VL] else Zeros(VL); bits(VL) result = Z[d, VL]; for e = 0 to elements-1 if ActivePredicateElement(mask, e, esize) then constant bits(esize) element = Elem[operand, e, esize]; constant bits(d_esize) res = FPConvertSVE(element<s_esize-1:0>, FPCR, d_esize); Elem[result, e, esize] = ZeroExtend(res, esize); Z[d, VL] = result;

Operational information

This instruction might be immediately preceded in program order by a MOVPRFX instruction. The MOVPRFX must conform to all of the following requirements, otherwise the behavior of the MOVPRFX and this instruction is constrained unpredictable:


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

Copyright © 2010-2024 Arm Limited or its affiliates. All rights reserved. This document is Non-Confidential.