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- ; code: lang=asm-collection tabSize=8
- ; macros for placing interrupt vectors in the middle of a block of threaded code
- SPT_SKIP_INTVEC .macro
- dw spt_jp, .intvec_continue ; continue after the NMI vector
- PLACE_INTVEC
- ; ld sp,0
- reti
- .intvec_continue:
- .endm
- SPT_SKIP_NMIVEC .macro
- dw spt_jp, .nmivec_continue ; continue after the NMI vector
- ; PLACE_NMIVEC
- PLACE_VEC $66
- ; ld sp,0 ; on model 1, NMI is connected to reset button
- retn
- .nmivec_continue:
- .endm
- ; Start a threaded-code section by pointing to it with SP and issuing RET
- ; immediately following this macro should be the addresses (and optionally,
- ; parameters) for the threaded code
- SPTHREAD_BEGIN .macro
- .local threadstart
- ld sp,.`threadstart
- ret
- .`threadstart:
- .endm
- ; At the end of the threaded code section, place an address just beyond
- ; the list of addresses, to jump back to conventional code
- SPTHREAD_END .macro
- dw $+2
- .endm
- ; Save the stack pointer into the stack registers. This is analogous
- ; to pushing SP onto the (simulated) stack. The shadow registers hold
- ; two copies of SP, and effectively become a 2-element stack. This means
- ; that there can be up to two threaded code stack frames saved. The
- ; innermost threaded stack frame can call a third-level machine-code
- ; subroutine, but that subroutine can't make any further calls or run
- ; threaded code itself.
- SPTHREAD_SAVE .macro
- exx
- ex af,af' ; save flags because of the add hl,sp instruction
- ex de,hl
- ld hl,0 ; copy old sp to iy
- add hl,sp
- ex af,af'
- exx
- .endm
- ; The opposite of SPTHREAD_SAVE. Pops SP off the simulated stack in
- ; preparation for returning to the enclosing threaded stack frame.
- SPTHREAD_RESTORE .macro
- exx
- ld sp,hl ; resume from the thread location saved in hl'
- ex de,hl
- exx
- .endm
- ; The prologue for a subroutine that contains threaded code.
- SPTHREAD_ENTER .macro
- SPTHREAD_SAVE
- SPTHREAD_BEGIN
- .endm
- ; The epilogue for a subroutine that contains threaded code. To be followed by RET
- SPTHREAD_LEAVE .macro
- SPTHREAD_END
- SPTHREAD_RESTORE
- .endm
- MAC_SPT_CON_GOTO .macro row,col
- dw spt_con_goto, VBASE+(row*VLINE)+col
- .endm
- MAC_SPT_CON_OFFSET .macro row,col
- dw VBASE+(row*VLINE)+col
- .endm
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