FCLAMP

Multi-vector floating-point clamp to minimum/maximum number

This instruction clamps each floating-point element in the two or four destination vectors to between the floating-point minimum value in the corresponding element of the first source vector and the floating-point maximum value in the corresponding element of the second source vector and destructively places the clamped results in the corresponding elements of the two or four destination vectors.

Regardless of the value of FPCR.AH, the behavior is as follows for each minimum number and maximum number operation:

Negative zero compares less than positive zero.

If one value is numeric and the other is a quiet NaN, the result is the numeric value.

When FPCR.DN is 0, if either value is a signaling NaN or if both values are NaNs, the result is a quiet NaN.

When FPCR.DN is 1, if either value is a signaling NaN or if both values are NaNs, the result is Default NaN.

This instruction follows SME2 floating-point numerical behaviors corresponding to instructions that place their results in one or more SVE Z vectors.

This instruction is unpredicated.

Encoding: Two registers

Variants: FEAT_SME2 (ARMv9.3)

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
1	1	0	0	0	0	0	1	!= 00		1						1	1	0	0	0	0										0
								size			Zm											Zn					Zd				op

FCLAMP { <Zd1>.<T>-<Zd2>.<T> }, <Zn>.<T>, <Zm>.<T>

Decoding algorithm

if !IsFeatureImplemented(FEAT_SME2) then EndOfDecode(Decode_UNDEF);
constant integer esize = 8 << UInt(size);
constant integer n = UInt(Zn);
constant integer m = UInt(Zm);
constant integer d = UInt(Zd:'0');
constant integer nreg = 2;

Encoding: Four registers

Variants: FEAT_SME2 (ARMv9.3)

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
1	1	0	0	0	0	0	1	!= 00		1						1	1	0	0	1	0									0	0
								size			Zm											Zn					Zd				op

FCLAMP { <Zd1>.<T>-<Zd4>.<T> }, <Zn>.<T>, <Zm>.<T>

Decoding algorithm

if !IsFeatureImplemented(FEAT_SME2) then EndOfDecode(Decode_UNDEF);
constant integer esize = 8 << UInt(size);
constant integer n = UInt(Zn);
constant integer m = UInt(Zm);
constant integer d = UInt(Zd:'00');
constant integer nreg = 4;

Operation

CheckStreamingSVEEnabled();
constant integer VL = CurrentVL;
constant integer elements = VL DIV esize;
array [0..3] of bits(VL) results;

for r = 0 to nreg-1
    constant bits(VL) operand1 = Z[n, VL];
    constant bits(VL) operand2 = Z[m, VL];
    constant bits(VL) operand3 = Z[d+r, VL];
    for e = 0 to elements-1
        constant bits(esize) element1 = Elem[operand1, e, esize];
        constant bits(esize) element2 = Elem[operand2, e, esize];
        constant bits(esize) element3 = Elem[operand3, e, esize];
        constant bits(esize) maxelement = FPMaxNum(element1, element3, FPCR);
        Elem[results[r], e, esize] = FPMinNum(maxelement, element2, FPCR);

for r = 0 to nreg-1
    Z[d+r, VL] = results[r];

Explanations

<Zd1>: For the "Two registers" variant: is the name of the first scalable vector register of the destination multi-vector group, encoded as "Zd" times 2.
<Zd1>: For the "Four registers" variant: is the name of the first scalable vector register of the destination multi-vector group, encoded as "Zd" times 4.
<T>: <Zd2>: Is the name of the second scalable vector register of the destination multi-vector group, encoded as "Zd" times 2 plus 1.
<Zn>: Is the name of the first source scalable vector register, encoded in the "Zn" field.
<Zm>: Is the name of the second source scalable vector register, encoded in the "Zm" field.
<Zd4>: Is the name of the fourth scalable vector register of the destination multi-vector group, encoded as "Zd" times 4 plus 3.