SPA 5.0:Note that .pop and Pu can only be used with Sb(register).{@{!}Pg}LOP3.LUT{.X}{.pop}Pu, Rd, Ra, Rb, Rc, #Imm8{&req_6}{?sched};{@{!}Pg}LOP3.LUT{.X}{.pop}Rd{.CC}, Ra, Sb, Rc, #Imm8{&req_6}{?sched};{@{!}Pg}LOP3.lop{.X}{.pop}Pu, Rd, {~}Ra, {~}Rb, {~}Rc{&req_6}{?sched};.lop: logical operation { .AND, .OR, .XOR, .PASS_B } .pop: predicate operation { .F*, .T, .Z, .NZ } .X : Extended precision logical operation .CC : Write condition codes LOP3 allows the following source Sb: Sb(register) Sb(constant with immediate address) Sb(#IMM20){@{!}Pg}LOP3.lop{.X}{.pop}Rd{.CC}, {~}Ra, {~}Sb, {~}Rc{&req_6}{?sched};
An arbitrary bitwise logical function of three sources into one destination.
The #Imm8 specifies which logic function is desired. There are 2^(2^3) logic functions possible for 3 inputs,
so all such functions can be specified. The #Imm8 acts as the logic table for the desired function.
For each individual bit i, the result Rd[i] = LUT[ (Ra[i]<<2) | (Sb[i]<<1) | Rc[i] ].
Syntactic sugar is provided for .AND, .OR, .XOR, and .PASS_B, along with optional complements on Ra, Sb, and Rc. This provides similar syntax as LOP, but those are all assembled down to their respective #Imm8 values; a subset of these cases is shown below.
| logic function | LUT (#Imm8) value |
|---|---|
| .AND | 0b10000000 |
| .OR | 0b11111110 |
| .XOR | 0b10010110 |
| .PASS_B | 0b11001100 |
| It's also possible to emulate the negation of any input, such as: | |
| .AND with ~Sb and ~Rc | 0b00010000 |
| .OR with ~Ra and ~Rc | 0b11011111 |
| Similarly, one could easily use these functions: | |
| A ^ (B & (A ^ C)) | 0b10111000 |
| (A & B) | (A & C) | (B & C) | 0b11101000 |
An extended-precision logical operation is performed by processing words in order from least-significant to most-significant. This order is required so that the sign flag will be set correctly based on the msb of the most-significant word. The zero flag is accumulated by LOP3.X instructions.
If a predicate destination is specified, result of the predicate operation is written back to destination register.
Note that a .pop and predicate destination (Pu) can only be specified if Sb is a register.
LOP3.OR R0, R1, R2, R3; LOP3.AND P0, R0, R1, R2, R3; LOP3.LUT P0, R0, R1, R2, R3, 0x45;