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Diffstat (limited to 'main.s')
| -rw-r--r-- | main.s | 200 |
1 files changed, 200 insertions, 0 deletions
@@ -0,0 +1,200 @@ +||| -*- mode: gas; gas-comment-char: 124 -*- +||| z80 emulator for 68k calculators + +||| Astrid Smith +||| Project started: 2010-06-06 +||| GPL + +||| Yes, I use lots of big ascii art. With this much code, you need +||| something to catch your eye when scrolling through it. I suppose +||| I'll split it into different files later. + +||| Registers used: +||| +||| A7 68000 stack pointer +||| A6/epc emulated PC +||| A5 instruction table base pointer +||| A4 emulated SP +||| A3 pointer to flag_storage +||| A2 +||| A1 +||| A0 +||| +||| D0 current instruction, scratch for macros +||| D1 scratch for instructions +||| D2 further scratch +||| +||| +||| The following have their shadows in the top half of the register +||| D3/eaf = AF A is in the low byte, F in the high byte (yeah ... speed) +||| D4/ebc = BC B high, C low +||| D5/ede = DE D high, E low +||| D6/ehl = HL H high, L low +||| +||| IY is used more often so it's easier to get at. It can be slow +||| but I don't really care to go to the effort to make it so. +||| D7/eixy = IX (hi word), IY (low word) + + +||| emulated I and R are both in RAM + +.xdef _ti89 +|.xdef _ti92plus +.xdef __main +|.xdef _tigcc_native +.include "../tios.h" + +.include "global.inc" + +__main: + movem.l d0-d7/a0-a6,-(sp) + bsr init_load + bsr display_setup + + bsr emu_setup + lea emu_plain_op,a5 + + || ... aaaaand we're off! + jsr emu_run + bsr emu_teardown + + bsr display_teardown + bsr unload + movem.l (sp)+,d0-d7/a0-a6 + rts + +.include "ports.s" +.include "interrupts.s" +.include "flags.s" +.include "alu.s" + +emu_setup: + movea.l emu_op_00,a5 + lea emu_run,a2 + lea flag_storage,a3 + move.w #$4000,d1 + bsr deref + move.l a0,epc + move.l a0,esp + + rts + +emu_teardown: + rts + + +|| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||| +|| _ __ ___ ___ _ __ ___ ___ _ __ _ _ ||||||||||||||||||||||||||| +|| | '_ ` _ \ / _ \ '_ ` _ \ / _ \| '__| | | | \\\\\\\\\\\\\\\\\\\\\\\\\\\ +|| | | | | | | __/ | | | | | (_) | | | |_| | ||||||||||||||||||||||||||| +|| |_| |_| |_|\___|_| |_| |_|\___/|_| \__, | /////////////////////////// +|| of the virtual type |___/ ||||||||||||||||||||||||||| +|| =============================================JJJJJJJJJJJJJJJJJJJJJJJJJJJ + + || Take a virtual address in d1 and dereference it. Returns the + || host address in a0. Destroys a0, d0. +deref: | 76 cycles + 18 cycles for bsr + | 20 bytes to inline, saves 34 cycles per call + move.w d1,d0 + andi.w #$3FFF,d0 + movea.w d0,a0 + move.w d1,d0 + andi.w #$C000,d0 | Can cut this out by pre-masking the table. + rol.w #4,d0 + adda.l deref_table(pc,d0.w),a0 + rts + +.even +.data +deref_table: +mem_page_0: .long 0 | bank 0 / 0x0000 +mem_page_1: .long 0 | bank 1 / 0x4000 +mem_page_2: .long 0 | bank 2 / 0x8000 +mem_page_3: .long 0 | bank 3 / 0xc000 + +.xdef mem_page_0 +.xdef mem_page_1 +.xdef mem_page_2 +.xdef mem_page_3 + +mem_page_loc_0: .byte 0 +mem_page_loc_1: .byte 0 +mem_page_loc_2: .byte 0 +mem_page_loc_3: .byte 0 + +.xdef mem_page_loc_0 +.xdef mem_page_loc_1 +.xdef mem_page_loc_2 +.xdef mem_page_loc_3 + +pages: .long 0 + +.xdef pages + +.text + + || Take a physical address in a0 and turn it into a virtual + || address in d0 + || Destroys d0 +| XXX AFAICS, a1 is currently a scratch address register, so you can load deref_table in it, and then save some space: +| But you may wish to use it for other purposes in the future, so you needn't integrate that immediately. + + || Guessing this is 300 cycles. +underef: + move.l d2,-(a7) + lea deref_table(pc),a1 + move.l a0,d0 + clr.w d2 + sub.l (a1)+,d0 + bmi.s underef_not0 + cmpi.l #$4000,d0 + bmi.s underef_thatsit +underef_not0: + move.l a0,d0 + move.w #$4000,d2 + sub.l (a1)+,d0 + bmi.s underef_not1 + cmpi.l #$4000,d0 + bmi.s underef_thatsit +underef_not1: + move.l a0,d0 + move.w #$8000,d2 + sub.l (a1)+,d0 + bmi.s underef_not2 + cmpi.l #$4000,d0 + bmi.s underef_thatsit +underef_not2: + move.w #$c000,d2 + suba.l (a1)+,a0 + || if that fails too, well shit man! + moveq #0,d0 +underef_thatsit: + add.w d2,d0 + move.l (a7)+,d2 + rts + + +|| ========================================================================= +|| instruction instruction instruction ================================ +|| _ _ _ _ ================================ +|| __| (_)___ _ __ __ _| |_ ___| |__ ================================ +|| / _` | / __| '_ \ / _` | __/ __| '_ \ ================================ +|| | (_| | \__ \ |_) | (_| | || (__| | | | ================================ +|| \__,_|_|___/ .__/ \__,_|\__\___|_| |_| ================================ +|| |_| ================================= +|| ========== ======================================================== +|| ========================================================================= + +.include "opcodes.s" + +emu_run: + || XXX: make this actually return + DONE + rts + +emu_op_undo_cb: +emu_op_undo_dd: +emu_op_undo_ed: +emu_op_undo_fd: + rts + |