SCVTF -- A64

Convert to floating-point from the signed integer in each active 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 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 zero-extended to fill each destination element.

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

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); constant integer esize = 16; constant integer g = UInt(Pg); constant integer n = UInt(Zn); constant integer d = UInt(Zd); constant integer s_esize = 16; constant integer d_esize = 16; constant boolean unsigned = FALSE; constant FPRounding rounding = FPRoundingMode(FPCR); constant boolean merging = TRUE;

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

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE2p2) && !IsFeatureImplemented(FEAT_SME2p2) then EndOfDecode(Decode_UNDEF); constant integer esize = 16; constant integer g = UInt(Pg); constant integer n = UInt(Zn); constant integer d = UInt(Zd); constant integer s_esize = 16; constant integer d_esize = 16; constant boolean unsigned = FALSE; constant FPRounding rounding = FPRoundingMode(FPCR); constant boolean merging = FALSE;

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

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); 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; constant boolean unsigned = FALSE; constant FPRounding rounding = FPRoundingMode(FPCR); constant boolean merging = TRUE;

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

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE2p2) && !IsFeatureImplemented(FEAT_SME2p2) then EndOfDecode(Decode_UNDEF); 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; constant boolean unsigned = FALSE; constant FPRounding rounding = FPRoundingMode(FPCR); constant boolean merging = FALSE;

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

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); 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 = 32; constant boolean unsigned = FALSE; constant FPRounding rounding = FPRoundingMode(FPCR); constant boolean merging = TRUE;

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

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE2p2) && !IsFeatureImplemented(FEAT_SME2p2) then EndOfDecode(Decode_UNDEF); 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 = 32; constant boolean unsigned = FALSE; constant FPRounding rounding = FPRoundingMode(FPCR); constant boolean merging = FALSE;

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

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); 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; constant boolean unsigned = FALSE; constant FPRounding rounding = FPRoundingMode(FPCR); constant boolean merging = TRUE;

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

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE2p2) && !IsFeatureImplemented(FEAT_SME2p2) then EndOfDecode(Decode_UNDEF); 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; constant boolean unsigned = FALSE; constant FPRounding rounding = FPRoundingMode(FPCR); constant boolean merging = FALSE;

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

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); 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; constant boolean unsigned = FALSE; constant FPRounding rounding = FPRoundingMode(FPCR); constant boolean merging = TRUE;

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

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE2p2) && !IsFeatureImplemented(FEAT_SME2p2) then EndOfDecode(Decode_UNDEF); 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; constant boolean unsigned = FALSE; constant FPRounding rounding = FPRoundingMode(FPCR); constant boolean merging = FALSE;

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

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); 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; constant boolean unsigned = FALSE; constant FPRounding rounding = FPRoundingMode(FPCR); constant boolean merging = TRUE;

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

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE2p2) && !IsFeatureImplemented(FEAT_SME2p2) then EndOfDecode(Decode_UNDEF); 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; constant boolean unsigned = FALSE; constant FPRounding rounding = FPRoundingMode(FPCR); constant boolean merging = FALSE;

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

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); 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 = 64; constant boolean unsigned = FALSE; constant FPRounding rounding = FPRoundingMode(FPCR); constant boolean merging = TRUE;

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

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE2p2) && !IsFeatureImplemented(FEAT_SME2p2) then EndOfDecode(Decode_UNDEF); 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 = 64; constant boolean unsigned = FALSE; constant FPRounding rounding = FPRoundingMode(FPCR); constant boolean merging = 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(); 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 = if merging then Z[d, VL] else Zeros(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) fpval = FixedToFP(element<s_esize-1:0>, 0, unsigned, FPCR, rounding, d_esize); Elem[result, e, esize] = ZeroExtend(fpval, esize); Z[d, VL] = result;

Operational information

For the "16-bit to half-precision, merging" , "32-bit to half-precision, merging" , "32-bit to single-precision, merging" , "32-bit to double-precision, merging" , "64-bit to half-precision, merging" , "64-bit to single-precision, merging" , "64-bit to double-precision, 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.

Internal version only: aarchmrs v2024-12_rel, pseudocode v2024-12_rel ; Build timestamp: 2024-12-15T22:18

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	0	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	0	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	0	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	0	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	1	0	0	1	0	1	0	0	1	0	1	Pg			Zn					Zd
								opc					opc2		int_U