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Add PHX/PLX and PHY/PLY #3

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BigEd opened this issue Sep 1, 2011 · 1 comment

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BigEd commented Sep 1, 2011

These are quite difficult to replace with macros and very useful to preserve registers.

They are defined in 65C02

Owner Author

BigEd commented Apr 14, 2012

Arlet implementation notes from http://forum.6502.org/viewtopic.php?p=15834#p15834:

In the first place, the opcode mask needs to include the new opcode here
http://github.com/Arlet/verilog-6502/blob/c51aa17b6b1a4de23184815fd404b4670186f8ae/cpu.v#L877

Secondly, it needs an extra opcode mask to set src_reg to SEL_X register here
https://github.com/Arlet/verilog-6502/blob/c51aa17b6b1a4de23184815fd404b4670186f8ae/cpu.v#L1016

Of course, with all opcode extensions you have to watch out that the new opcode doesn't overlap with a "don't care" in one of the existing patterns.

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