From fb4663f2e36b6c69bb62b11d0690755bb691ceb3 Mon Sep 17 00:00:00 2001 From: ekeeke31 Date: Fri, 18 Jun 2010 11:02:10 +0000 Subject: [PATCH] More changes to Z80 bus request/reset --- source/genesis.c | 114 ++++++++++++++++++++++++++--------------------- 1 file changed, 62 insertions(+), 52 deletions(-) diff --git a/source/genesis.c b/source/genesis.c index 3f49b17..e8c06ba 100644 --- a/source/genesis.c +++ b/source/genesis.c @@ -138,15 +138,15 @@ void gen_hardreset(void) m68k_memory_map[0].base = bios_rom; } - /* Reset CPU cycles (check EA logo corruption, no glitches for Skitchin/Budokan on PAL 60hz MD2 with TMSS) */ - mcycles_68k = mcycles_z80 = (rand() % lines_per_frame) * MCYCLES_PER_LINE; + /* Reset CPU cycles */ + mcycles_68k = mcycles_z80 = 0; - /* Z80 bus is released & Z80 reset is asserted */ - zstate = 0; + /* Z80 bus is released & Z80 is stopped */ m68k_memory_map[0xa0].read8 = m68k_read_bus_8; m68k_memory_map[0xa0].read16 = m68k_read_bus_16; m68k_memory_map[0xa0].write8 = m68k_unused_8_w; m68k_memory_map[0xa0].write16 = m68k_unused_16_w; + zstate = 0; /* Assume default bank is $000000-$007FFF */ zbank = 0; @@ -256,20 +256,16 @@ unsigned int gen_bankswitch_r(void) /*----------------------------------------------------------------------- Z80 Bus controller chip functions -----------------------------------------------------------------------*/ -void gen_zbusreq_w(unsigned int state, unsigned int cycles) +void gen_zbusreq_w(unsigned int data, unsigned int cycles) { - if (state) /* !ZBUSREQ asserted */ + if (data) /* !ZBUSREQ asserted */ { - /* if z80 was running, resynchronize with 68k */ + /* check if Z80 is going to be stopped */ if (zstate == 1) - z80_run(cycles); - - /* update Z80 bus status */ - zstate |= 2; - - /* check if Z80 reset is released */ - if (zstate & 1) { + /* resynchronize with 68k */ + z80_run(cycles); + /* enable 68k access to Z80 bus */ _m68k_memory_map *base = &m68k_memory_map[0xa0]; base->read8 = z80_read_byte; @@ -277,42 +273,48 @@ void gen_zbusreq_w(unsigned int state, unsigned int cycles) base->write8 = z80_write_byte; base->write16 = z80_write_word; } + + /* update Z80 bus status */ + zstate |= 2; } else /* !ZBUSREQ released */ { - /* if z80 is restarted, resynchronize with 68k */ + /* check if Z80 is going to be restarted */ if (zstate == 3) - mcycles_z80 = cycles; + { + /* resynchronize with 68k */ + mcycles_z80 = cycles; + + /* disable 68k access to Z80 bus */ + _m68k_memory_map *base = &m68k_memory_map[0xa0]; + base->read8 = m68k_read_bus_8; + base->read16 = m68k_read_bus_16; + base->write8 = m68k_unused_8_w; + base->write16 = m68k_unused_16_w; + } /* update Z80 bus status */ zstate &= 1; - - /* disable 68k access */ - _m68k_memory_map *base = &m68k_memory_map[0xa0]; - base->read8 = m68k_read_bus_8; - base->read16 = m68k_read_bus_16; - base->write8 = m68k_unused_8_w; - base->write16 = m68k_unused_16_w; } } -void gen_zreset_w(unsigned int state, unsigned int cycles) +void gen_zreset_w(unsigned int data, unsigned int cycles) { - /* detect !ZRESET transitions */ - if (state == (zstate & 1)) - return; - - if (state) /* !ZRESET released */ + if (data) /* !ZRESET released */ { - /* if z80 is restarted, resynchronize with 68k */ - if (!zstate) - mcycles_z80 = cycles; - - /* update Z80 bus status */ - zstate |= 1; - - /* check if Z80 bus has been requested */ - if (zstate & 2) + /* check if Z80 is going to be restarted */ + if (zstate == 0) + { + /* resynchronize with 68k */ + mcycles_z80 = cycles; + + /* reset Z80 & YM2612 */ + z80_reset(); + fm_reset(cycles); + } + + /* check if 68k access to Z80 bus is granted */ + else if (zstate == 2) { /* enable 68k access to Z80 bus */ _m68k_memory_map *base = &m68k_memory_map[0xa0]; @@ -321,33 +323,41 @@ void gen_zreset_w(unsigned int state, unsigned int cycles) base->write8 = z80_write_byte; base->write16 = z80_write_word; } + + /* update Z80 bus status */ + zstate |= 1; } else /* !ZRESET asserted */ { - /* if z80 was running, resynchronize with 68k */ + /* check if Z80 is going to be stopped */ if (zstate == 1) + { + /* resynchronize with 68k */ z80_run(cycles); - - /* reset Z80 & YM2612 */ - z80_reset(); + } + + /* check if 68k had access to Z80 bus */ + else if (zstate == 3) + { + /* disable 68k access to Z80 bus */ + _m68k_memory_map *base = &m68k_memory_map[0xa0]; + base->read8 = m68k_read_bus_8; + base->read16 = m68k_read_bus_16; + base->write8 = m68k_unused_8_w; + base->write16 = m68k_unused_16_w; + } + + /* stop YM2612 */ fm_reset(cycles); /* update Z80 bus status */ zstate &= 2; - - /* disable 68k access */ - _m68k_memory_map *base = &m68k_memory_map[0xa0]; - base->read8 = m68k_read_bus_8; - base->read16 = m68k_read_bus_16; - base->write8 = m68k_unused_8_w; - base->write16 = m68k_unused_16_w; } - } -void gen_zbank_w (unsigned int state) +void gen_zbank_w (unsigned int data) { - zbank = ((zbank >> 1) | ((state & 1) << 23)) & 0xFF8000; + zbank = ((zbank >> 1) | ((data & 1) << 23)) & 0xFF8000; } int z80_irq_callback (int param)