USDOT (vector)
Dot product with unsigned and signed integers (vector)
This instruction performs the dot product of
the four unsigned 8-bit integer values in each 32-bit element of the first source register with
the four signed 8-bit integer values in the corresponding 32-bit element of the second source
register, accumulating the result into the corresponding 32-bit element of the destination
register.
From Armv8.2 to Armv8.5, this is an OPTIONAL instruction.
From Armv8.6 it is mandatory for implementations that include Advanced SIMD to support it.
ID_AA64ISAR1_EL1.I8MM indicates whether this instruction is supported.
If PSTATE.DIT is 1:
The execution time of this instruction is independent of:
The values of the data supplied in any of its registers.
The values of the NZCV flags.
The response of this instruction to asynchronous exceptions does not vary based on:
The values of the data supplied in any of its registers.
The values of the NZCV flags.
0
0
0
1
1
1
0
1
0
0
1
0
0
1
1
1
USDOT <Vd>.<Ta>, <Vn>.<Tb>, <Vm>.<Tb>
if !IsFeatureImplemented(FEAT_I8MM) then UNDEFINED;
constant integer d = UInt(Rd);
constant integer n = UInt(Rn);
constant integer m = UInt(Rm);
constant integer datasize = 64 << UInt(Q);
constant integer elements = datasize DIV 32;
<Vd>
Is the name of the SIMD&FP third source and destination register, encoded in the "Rd" field.
<Ta>
Is an arrangement specifier,
<Vn>
Is the name of the first SIMD&FP source register, encoded in the "Rn" field.
<Tb>
Is an arrangement specifier,
<Vm>
Is the name of the second SIMD&FP source register, encoded in the "Rm" field.
CheckFPAdvSIMDEnabled64();
constant bits(datasize) operand1 = V[n, datasize];
constant bits(datasize) operand2 = V[m, datasize];
constant bits(datasize) operand3 = V[d, datasize];
bits(datasize) result;
for e = 0 to elements-1
bits(32) res = Elem[operand3, e, 32];
for b = 0 to 3
constant integer element1 = UInt(Elem[operand1, 4 * e + b, 8]);
constant integer element2 = SInt(Elem[operand2, 4 * e + b, 8]);
res = res + element1 * element2;
Elem[result, e, 32] = res;
V[d, datasize] = result;