#include .section .text.keepboot *------------------------------------------------------- * * Sega startup code for the GNU Assembler * Translated from: * Sega startup code for the Sozobon C compiler * Written by Paul W. Lee * Modified by Charles Coty * Modified by Stephane Dallongeville * *------------------------------------------------------- .globl rom_header .org 0x00000000 _Start_Of_Rom: _Vecteurs_68K: dc.l __stack /* Stack address */ dc.l _Entry_Point /* Program start address */ dc.l _Bus_Error dc.l _Address_Error dc.l _Illegal_Instruction dc.l _Zero_Divide dc.l _Chk_Instruction dc.l _Trapv_Instruction dc.l _Privilege_Violation dc.l _Trace dc.l _Line_1010_Emulation dc.l _Line_1111_Emulation dc.l _Error_Exception, _Error_Exception, _Error_Exception, _Error_Exception dc.l _Error_Exception, _Error_Exception, _Error_Exception, _Error_Exception dc.l _Error_Exception, _Error_Exception, _Error_Exception, _Error_Exception dc.l _Error_Exception dc.l _INT dc.l _EXTINT dc.l _INT dc.l hintCaller dc.l _INT dc.l _VINT dc.l _INT dc.l _trap_0 /* Resume supervisor task */ dc.l _INT,_INT,_INT,_INT,_INT,_INT,_INT dc.l _INT,_INT,_INT,_INT,_INT,_INT,_INT,_INT dc.l _INT,_INT,_INT,_INT,_INT,_INT,_INT,_INT dc.l _INT,_INT,_INT,_INT,_INT,_INT,_INT,_INT rom_header: .incbin "out/rom_header.bin", 0, 0x100 _Entry_Point: * disable interrupts move #0x2700,%sr * Configure a USER_STACK_LENGTH bytes user stack at bottom, and system stack on top of it move %sp, %usp sub #USER_STACK_LENGTH, %sp * Halt Z80 (need to be done as soon as possible on reset) move.l #0xA11100,%a0 /* Z80_HALT_PORT */ move.w #0x0100,%d0 move.w %d0,(%a0) /* HALT Z80 */ move.w %d0,0x0100(%a0) /* END RESET Z80 */ tst.l 0xa10008 bne.s SkipInit tst.w 0xa1000c bne.s SkipInit * Check Version Number move.b -0x10ff(%a0),%d0 andi.b #0x0f,%d0 beq.s NoTMSS * Sega Security Code (SEGA) move.l #0x53454741,0x2f00(%a0) NoTMSS: jmp _start_entry SkipInit: jmp _reset_entry *------------------------------------------------ * * interrupt functions * *------------------------------------------------ _INT: movem.l %d0-%d1/%a0-%a1,-(%sp) move.l intCB, %a0 jsr (%a0) movem.l (%sp)+,%d0-%d1/%a0-%a1 rte _EXTINT: movem.l %d0-%d1/%a0-%a1,-(%sp) move.l eintCB, %a0 jsr (%a0) movem.l (%sp)+,%d0-%d1/%a0-%a1 rte _VINT: btst #5, (%sp) /* Skip context switch if not in user task */ bne.s no_user_task tst.w task_lock bne.s 1f move.w #0, -(%sp) /* TSK_superPend() will return 0 */ bra.s unlock /* If lock == 0, supervisor task is not locked */ 1: bcs.s no_user_task /* If lock < 0, super is locked with infinite wait */ subq.w #1, task_lock /* Locked with wait, subtract 1 to the frame count */ bne.s no_user_task /* And do not unlock if we did not reach 0 */ move.w #1, -(%sp) /* TSK_superPend() will return 1 */ unlock: /* Save bg task registers (excepting a7, that is stored in usp) */ move.l %a0, task_regs lea (task_regs + UTSK_REGS_LEN), %a0 movem.l %d0-%d7/%a1-%a6, -(%a0) move.w (%sp)+, %d0 /* Load return value previously pushed to stack */ move.w (%sp)+, task_sr /* Pop user task sr and pc, and save them, */ move.l (%sp)+, task_pc /* so they can be restored later. */ movem.l (%sp)+, %d2-%d7/%a2-%a6 /* Restore non clobberable registers */ no_user_task: /* At this point, we always have in the stack the SR and PC of the task */ /* we want to jump after processing the interrupt, that might be the */ /* point where we came from (if there is no context switch) or the */ /* supervisor task (if we unlocked it). */ movem.l %d0-%d1/%a0-%a1,-(%sp) ori.w #0x0001, intTrace /* in V-Int */ addq.l #1, vtimer /* increment frame counter (more a vint counter) */ move.l z80VIntCB, %a0 /* load Z80 V-Int handler */ jsr (%a0) /* call user callback */ btst #1, VBlankProcess+1 /* PROCESS_BITMAP_TASK ? (use VBlankProcess+1 as btst is a byte operation) */ beq.s no_bmp_task jsr BMP_doVBlankProcess /* do BMP vblank task */ no_bmp_task: move.l vintCB, %a0 /* load user callback */ jsr (%a0) /* call user callback */ andi.w #0xFFFE, intTrace /* out V-Int */ movem.l (%sp)+,%d0-%d1/%a0-%a1 rte *------------------------------------------------ * * Copyright (c) 1988 by Sozobon, Limited. Author: Johann Ruegg * * Permission is granted to anyone to use this software for any purpose * on any computer system, and to redistribute it freely, with the * following restrictions: * 1) No charge may be made other than reasonable charges for reproduction. * 2) Modified versions must be clearly marked as such. * 3) The authors are not responsible for any harmful consequences * of using this software, even if they result from defects in it. * *------------------------------------------------ ldiv: move.l 4(%a7),%d0 bpl ld1 neg.l %d0 ld1: move.l 8(%a7),%d1 bpl ld2 neg.l %d1 eor.b #0x80,4(%a7) ld2: bsr i_ldiv /* d0 = d0/d1 */ tst.b 4(%a7) bpl ld3 neg.l %d0 ld3: rts lmul: move.l 4(%a7),%d0 bpl lm1 neg.l %d0 lm1: move.l 8(%a7),%d1 bpl lm2 neg.l %d1 eor.b #0x80,4(%a7) lm2: bsr i_lmul /* d0 = d0*d1 */ tst.b 4(%a7) bpl lm3 neg.l %d0 lm3: rts lrem: move.l 4(%a7),%d0 bpl lr1 neg.l %d0 lr1: move.l 8(%a7),%d1 bpl lr2 neg.l %d1 lr2: bsr i_ldiv /* d1 = d0%d1 */ move.l %d1,%d0 tst.b 4(%a7) bpl lr3 neg.l %d0 lr3: rts ldivu: move.l 4(%a7),%d0 move.l 8(%a7),%d1 bsr i_ldiv rts lmulu: move.l 4(%a7),%d0 move.l 8(%a7),%d1 bsr i_lmul rts lremu: move.l 4(%a7),%d0 move.l 8(%a7),%d1 bsr i_ldiv move.l %d1,%d0 rts * * A in d0, B in d1, return A*B in d0 * i_lmul: move.l %d3,%a2 /* save d3 */ move.w %d1,%d2 mulu %d0,%d2 /* d2 = Al * Bl */ move.l %d1,%d3 swap %d3 mulu %d0,%d3 /* d3 = Al * Bh */ swap %d0 mulu %d1,%d0 /* d0 = Ah * Bl */ add.l %d3,%d0 /* d0 = (Ah*Bl + Al*Bh) */ swap %d0 clr.w %d0 /* d0 = (Ah*Bl + Al*Bh) << 16 */ add.l %d2,%d0 /* d0 = A*B */ move.l %a2,%d3 /* restore d3 */ rts * *A in d0, B in d1, return A/B in d0, A%B in d1 * i_ldiv: tst.l %d1 bne nz1 * divide by zero * divu #0,%d0 /* cause trap */ move.l #0x80000000,%d0 move.l %d0,%d1 rts nz1: move.l %d3,%a2 /* save d3 */ cmp.l %d1,%d0 bhi norm beq is1 * AB and B is not 0 norm: cmp.l #1,%d1 bne not1 * B==1, so ret A, rem 0 clr.l %d1 move.l %a2,%d3 /* restore d3 */ rts * check for A short (implies B short also) not1: cmp.l #0xffff,%d0 bhi slow * A short and B short -- use 'divu' divu %d1,%d0 /* d0 = REM:ANS */ swap %d0 /* d0 = ANS:REM */ clr.l %d1 move.w %d0,%d1 /* d1 = REM */ clr.w %d0 swap %d0 move.l %a2,%d3 /* restore d3 */ rts * check for B short slow: cmp.l #0xffff,%d1 bhi slower * A long and B short -- use special stuff from gnu move.l %d0,%d2 clr.w %d2 swap %d2 divu %d1,%d2 /* d2 = REM:ANS of Ahi/B */ clr.l %d3 move.w %d2,%d3 /* d3 = Ahi/B */ swap %d3 move.w %d0,%d2 /* d2 = REM << 16 + Alo */ divu %d1,%d2 /* d2 = REM:ANS of stuff/B */ move.l %d2,%d1 clr.w %d1 swap %d1 /* d1 = REM */ clr.l %d0 move.w %d2,%d0 add.l %d3,%d0 /* d0 = ANS */ move.l %a2,%d3 /* restore d3 */ rts * A>B, B > 1 slower: move.l #1,%d2 clr.l %d3 moreadj: cmp.l %d0,%d1 bhs adj add.l %d2,%d2 add.l %d1,%d1 bpl moreadj * we shifted B until its >A or sign bit set * we shifted #1 (d2) along with it adj: cmp.l %d0,%d1 bhi ltuns or.l %d2,%d3 sub.l %d1,%d0 ltuns: lsr.l #1,%d1 lsr.l #1,%d2 bne adj * d3=answer, d0=rem move.l %d0,%d1 move.l %d3,%d0 move.l %a2,%d3 /* restore d3 */ rts