Created
May 7, 2016 06:50
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Accessing byte at offset from stack pointer on 6502
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| tsx ; transfer stack pointer to X register | |
| stx scratch ; store X in RAM | |
| ldx #$01 ; load 0x01 into X | |
| stx scratch+1 ; store X in RAM | |
| ldx offset ; load offset into X | |
| lda (scratch,x) ; perform an indirect load from *(scratch + X) into A | |
| 1+2+2+2+2+2 bytes = 11 bytes | |
| 2+3+2+3+3+6 cycles = 19 cycles | |
| ; clobbers two of the 6502's three general-purpose registers |
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