.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 dc.l _Entry_Point 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 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 512 bytes user stack at bottom, and system stack on top of it move %sp, %usp sub #512, %sp * Halt Z80 (need to be done as soon as possible on reset) move.l #0xA11100,%a0 move.w #0x0100,%d0 move.w %d0,(%a0) move.w %d0,0x0100(%a0) 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) bne.s no_user_task tst.w task_lock bne.s 1f move.w #0, -(%sp) bra.s unlock 1: bcs.s no_user_task subq.w #1, task_lock bne.s no_user_task move.w #1, -(%sp) unlock: move.l %a0, task_regs lea (task_regs + (15 * 4)), %a0 movem.l %d0-%d7/%a1-%a6, -(%a0) move.w (%sp)+, %d0 move.w (%sp)+, task_sr move.l (%sp)+, task_pc movem.l (%sp)+, %d2-%d7/%a2-%a6 no_user_task: movem.l %d0-%d1/%a0-%a1,-(%sp) ori.w #0x0001, intTrace addq.l #1, vtimer move.l z80VIntCB, %a0 jsr (%a0) btst #1, VBlankProcess+1 beq.s no_bmp_task jsr BMP_doVBlankProcess no_bmp_task: move.l vintCB, %a0 jsr (%a0) andi.w #0xFFFE, intTrace 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 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 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 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 move.w %d1,%d2 mulu %d0,%d2 move.l %d1,%d3 swap %d3 mulu %d0,%d3 swap %d0 mulu %d1,%d0 add.l %d3,%d0 swap %d0 clr.w %d0 add.l %d2,%d0 move.l %a2,%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 move.l #0x80000000,%d0 move.l %d0,%d1 rts nz1: move.l %d3,%a2 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 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 swap %d0 clr.l %d1 move.w %d0,%d1 clr.w %d0 swap %d0 move.l %a2,%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 clr.l %d3 move.w %d2,%d3 swap %d3 move.w %d0,%d2 divu %d1,%d2 move.l %d2,%d1 clr.w %d1 swap %d1 clr.l %d0 move.w %d2,%d0 add.l %d3,%d0 move.l %a2,%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 rts