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Cleaning up definitions, and preparing for multitasking.

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Russell-S-Harper
2018-10-04 21:03:55 -04:00
parent 65267903c1
commit c3b51fe912
2 changed files with 37 additions and 20 deletions
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35
common/common.h
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@@ -47,7 +47,7 @@
; CMR pq 0f pq F <- Rp <=> Rq - compare registers
; 40 bytes in page zero for common registers
_R0 = $b8
_R0 = $100 - 4 * (10 + 9)
_R1 = _R0 + 4
_R2 = _R1 + 4
_R3 = _R2 + 4
@@ -58,15 +58,16 @@ _R7 = _R6 + 4
_R8 = _R7 + 4
_R9 = _R8 + 4
; 32 bytes in page zero for internal registers
_I0 = $e0 ; workspace
; 36 bytes in page zero for internal registers
_I0 = _R9 + 4 ; workspace
_I1 = _I0 + 4
_I2 = _I1 + 4
_I3 = _I2 + 4
_I4 = _I3 + 4
_I5 = _I4 + 4
_I6 = _I5 + 4 ; register I6 maintains common status
_I7 = _I6 + 4 ; register I7 saves/restores processor status
_I7 = _I6 + 4 ; register I7 maintains process information for context switching
_I8 = _I7 + 4 ; register I8 saves/restores processor status
; register I6 maintains common status
; (dd cc bb aa) aa: index for register stack RS / ccbb: program counter PC / dd: flags F UONPZLGE
@@ -86,21 +87,33 @@ _F_N = 32 ; if Rr < 0.0 (after TST)
_F_O = 64 ; if overflow (after arithmetic operations)
_F_U = 128 ; if underflow (after arithmetic operations)
; register I7 saves/restores processor status
; register I7 maintains process information for context switching
_PST = _I7 ; current process status
_PSI = _PST + 1 ; process stack index to save/restore
_PD0 = _PSI + 1 ; two bytes for process
_PD1 = _PD0 + 1
; register I8 saves/restores processor status
; (dd cc bb aa) aa: accumulator, bb: index X, cc: index Y, dd: processor status
_ACC = _I7 ; saved accumulator to restore
_ACC = _I8 ; saved accumulator to restore
_IDX = _ACC + 1 ; saved index X to restore
_IDY = _IDX + 1 ; saved index Y to restore
_PS = _IDY + 1 ; saved processor status to restore
; 224 bytes of page two
; 6502 stack resides on page one
; using some of page two for register stack
_RS = $200 ; register stack
_RSS = (FN_FX - _RS) ; register stack size
_RSS = _R0 ; register stack size
; for context switching, at least _R0 to FN_FX-1 plus one byte for the stack pointer need to be saved and restored
; for context switching, _R0 to _RS + _RSS - 1 needs to be saved and restored
; this should comprise two pages or 512 bytes
; last 32 bytes of page two
FN_FX = $2e0 ; list of system and user functions
_PR = _RS + _RSS ; running processes
_PRS = FN_FX - _PR ; running process size
; 32 bytes of page two
FN_FX = $300 - 2 * 16 ; list of system and user functions
; function constants
_ESC_C = $00