FCVTZS -- A64

This instruction converts to the signed integer nearer to zero from each active floating-point element of the source vector, and places the results in the corresponding elements of the destination vector. Inactive elements in the destination vector register remain unmodified or are set to zero, depending on whether merging or zeroing predication is selected.

If 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 sign-extended to fill each destination element.

Half-precision to 16-bit, merging
(FEAT_SVE || FEAT_SME)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 16; let g : integer = UInt(Pg); let n : integer = UInt(Zn); let d : integer = UInt(Zd); let s_esize : integer{} = 16; let d_esize : integer{} = 16; let unsigned : boolean = FALSE; let rounding : FPRounding = FPRounding_ZERO; let merging : boolean = TRUE;

Half-precision to 16-bit, zeroing
(FEAT_SVE2p2 || FEAT_SME2p2)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE2p2) && !IsFeatureImplemented(FEAT_SME2p2) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 16; let g : integer = UInt(Pg); let n : integer = UInt(Zn); let d : integer = UInt(Zd); let s_esize : integer{} = 16; let d_esize : integer{} = 16; let unsigned : boolean = FALSE; let rounding : FPRounding = FPRounding_ZERO; let merging : boolean = FALSE;

Half-precision to 32-bit, merging
(FEAT_SVE || FEAT_SME)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 32; let g : integer = UInt(Pg); let n : integer = UInt(Zn); let d : integer = UInt(Zd); let s_esize : integer{} = 16; let d_esize : integer{} = 32; let unsigned : boolean = FALSE; let rounding : FPRounding = FPRounding_ZERO; let merging : boolean = TRUE;

Half-precision to 32-bit, zeroing
(FEAT_SVE2p2 || FEAT_SME2p2)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE2p2) && !IsFeatureImplemented(FEAT_SME2p2) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 32; let g : integer = UInt(Pg); let n : integer = UInt(Zn); let d : integer = UInt(Zd); let s_esize : integer{} = 16; let d_esize : integer{} = 32; let unsigned : boolean = FALSE; let rounding : FPRounding = FPRounding_ZERO; let merging : boolean = FALSE;

Half-precision to 64-bit, merging
(FEAT_SVE || FEAT_SME)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 64; let g : integer = UInt(Pg); let n : integer = UInt(Zn); let d : integer = UInt(Zd); let s_esize : integer{} = 16; let d_esize : integer{} = 64; let unsigned : boolean = FALSE; let rounding : FPRounding = FPRounding_ZERO; let merging : boolean = TRUE;

Half-precision to 64-bit, zeroing
(FEAT_SVE2p2 || FEAT_SME2p2)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE2p2) && !IsFeatureImplemented(FEAT_SME2p2) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 64; let g : integer = UInt(Pg); let n : integer = UInt(Zn); let d : integer = UInt(Zd); let s_esize : integer{} = 16; let d_esize : integer{} = 64; let unsigned : boolean = FALSE; let rounding : FPRounding = FPRounding_ZERO; let merging : boolean = FALSE;

Single-precision to 32-bit, merging
(FEAT_SVE || FEAT_SME)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 32; let g : integer = UInt(Pg); let n : integer = UInt(Zn); let d : integer = UInt(Zd); let s_esize : integer{} = 32; let d_esize : integer{} = 32; let unsigned : boolean = FALSE; let rounding : FPRounding = FPRounding_ZERO; let merging : boolean = TRUE;

Single-precision to 32-bit, zeroing
(FEAT_SVE2p2 || FEAT_SME2p2)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE2p2) && !IsFeatureImplemented(FEAT_SME2p2) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 32; let g : integer = UInt(Pg); let n : integer = UInt(Zn); let d : integer = UInt(Zd); let s_esize : integer{} = 32; let d_esize : integer{} = 32; let unsigned : boolean = FALSE; let rounding : FPRounding = FPRounding_ZERO; let merging : boolean = FALSE;

Single-precision to 64-bit, merging
(FEAT_SVE || FEAT_SME)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 64; let g : integer = UInt(Pg); let n : integer = UInt(Zn); let d : integer = UInt(Zd); let s_esize : integer{} = 32; let d_esize : integer{} = 64; let unsigned : boolean = FALSE; let rounding : FPRounding = FPRounding_ZERO; let merging : boolean = TRUE;

Single-precision to 64-bit, zeroing
(FEAT_SVE2p2 || FEAT_SME2p2)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE2p2) && !IsFeatureImplemented(FEAT_SME2p2) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 64; let g : integer = UInt(Pg); let n : integer = UInt(Zn); let d : integer = UInt(Zd); let s_esize : integer{} = 32; let d_esize : integer{} = 64; let unsigned : boolean = FALSE; let rounding : FPRounding = FPRounding_ZERO; let merging : boolean = FALSE;

Double-precision to 32-bit, merging
(FEAT_SVE || FEAT_SME)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 64; let g : integer = UInt(Pg); let n : integer = UInt(Zn); let d : integer = UInt(Zd); let s_esize : integer{} = 64; let d_esize : integer{} = 32; let unsigned : boolean = FALSE; let rounding : FPRounding = FPRounding_ZERO; let merging : boolean = TRUE;

Double-precision to 32-bit, zeroing
(FEAT_SVE2p2 || FEAT_SME2p2)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE2p2) && !IsFeatureImplemented(FEAT_SME2p2) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 64; let g : integer = UInt(Pg); let n : integer = UInt(Zn); let d : integer = UInt(Zd); let s_esize : integer{} = 64; let d_esize : integer{} = 32; let unsigned : boolean = FALSE; let rounding : FPRounding = FPRounding_ZERO; let merging : boolean = FALSE;

Double-precision to 64-bit, merging
(FEAT_SVE || FEAT_SME)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 64; let g : integer = UInt(Pg); let n : integer = UInt(Zn); let d : integer = UInt(Zd); let s_esize : integer{} = 64; let d_esize : integer{} = 64; let unsigned : boolean = FALSE; let rounding : FPRounding = FPRounding_ZERO; let merging : boolean = TRUE;

Double-precision to 64-bit, zeroing
(FEAT_SVE2p2 || FEAT_SME2p2)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE2p2) && !IsFeatureImplemented(FEAT_SME2p2) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 64; let g : integer = UInt(Pg); let n : integer = UInt(Zn); let d : integer = UInt(Zd); let s_esize : integer{} = 64; let d_esize : integer{} = 64; let unsigned : boolean = FALSE; let rounding : FPRounding = FPRounding_ZERO; let merging : boolean = FALSE;

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(); let VL : integer{} = CurrentVL(); let PL : integer{} = VL DIV 8; let elements : integer = VL DIV esize; let mask : bits(PL) = P{}(g); let operand : bits(VL) = if AnyActiveElement{PL}(mask, esize) then Z{VL}(n) else Zeros{VL}; var result : bits(VL) = if merging then Z{VL}(d) else Zeros{VL}; for e = 0 to elements-1 do if ActivePredicateElement{PL}(mask, e, esize) then let element : bits(esize) = operand[e*:esize]; let res : bits(d_esize) = FPToFixed{d_esize, s_esize}(element[s_esize-1:0], 0, unsigned, FPCR(), rounding); result[e*:esize] = Extend{esize}(res, unsigned); end; end; Z{VL}(d) = result;

Operational information

For the "Half-precision to 16-bit, merging" , "Half-precision to 32-bit, merging" , "Half-precision to 64-bit, merging" , "Single-precision to 32-bit, merging" , "Single-precision to 64-bit, merging" , "Double-precision to 32-bit, merging" , "Double-precision to 64-bit, merging" variants:

The merging variant of 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 the merging variant of this instruction is CONSTRAINED UNPREDICTABLE:

The MOVPRFX can be predicated or unpredicated.
A predicated MOVPRFX must use the same governing predicate register as the merging variant this instruction.
A predicated MOVPRFX must use the larger of the destination element size and first source element size in the preferred disassembly of the merging variant of this instruction.
The MOVPRFX must specify the same destination register as the merging variant of this instruction.
The destination register must not refer to architectural register state referenced by any other source operand register of the merging variant of this instruction.

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

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1	1	0	0	1	0	1	0	1	0	1	1	0	1	0	1	0	1	Pg			Zn					Zd
								opc					opc2		int_U

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1	1	0	0	1	0	0	0	1	0	1	1	1	1	0	1	1	0	Pg			Zn					Zd
								opc							o2		o3	int_U

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1	1	0	0	1	0	1	0	1	0	1	1	1	0	0	1	0	1	Pg			Zn					Zd
								opc					opc2		int_U

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1	1	0	0	1	0	0	0	1	0	1	1	1	1	1	1	0	0	Pg			Zn					Zd
								opc							o2		o3	int_U

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1	1	0	0	1	0	1	0	1	0	1	1	1	1	0	1	0	1	Pg			Zn					Zd
								opc					opc2		int_U