The YGREC8's Manual : the XOR opcode

Created dim. 29 oct. 2023 23:40:23 CET by whygee@f-cpu.org

PRELIMINARY / WORK IN PROGRESS

Encoding

Description

This opcode takes the SRI operand and computes a boolean exclusive OR (difference) with the SND operand, then writes the result back into SND.

If the destination register (SND unless instructed otherwise by PF) is PC, this performs a jump. But it's pretty dumb.

Effects

XOR affects the Sign and Zero flags but not the Carry.

Forms

This is a core operation that supports all 3 types of operand for SRI:

• Imm8: an immediate field of 8 bits is taken directly from the instruction.
• Imm4: a sign-extended immediate value. Can be inhibited by a one of 8 conditions.
• SRI: one of the 8 registers. Can be inhibited by a one of 16 conditions.

Examples

XOR R1 R2 ; R2 = R2 ^ R1

XOR 123 R3 ; R3 = R3 ^ 123

; XOR R2 into R1 if external bit 1 is set
XOR R2 R1 IF1

; flip bit 1 of R3 if the last result was positive
XOR 2 R3 IFNS