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https://github.com/ekeeke/Genesis-Plus-GX.git
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More changes to Z80 bus request/reset
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parent
84a395dbf3
commit
fb4663f2e3
114
source/genesis.c
114
source/genesis.c
@ -138,15 +138,15 @@ void gen_hardreset(void)
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m68k_memory_map[0].base = bios_rom;
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}
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/* Reset CPU cycles (check EA logo corruption, no glitches for Skitchin/Budokan on PAL 60hz MD2 with TMSS) */
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mcycles_68k = mcycles_z80 = (rand() % lines_per_frame) * MCYCLES_PER_LINE;
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/* Reset CPU cycles */
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mcycles_68k = mcycles_z80 = 0;
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/* Z80 bus is released & Z80 reset is asserted */
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zstate = 0;
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/* Z80 bus is released & Z80 is stopped */
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m68k_memory_map[0xa0].read8 = m68k_read_bus_8;
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m68k_memory_map[0xa0].read16 = m68k_read_bus_16;
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m68k_memory_map[0xa0].write8 = m68k_unused_8_w;
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m68k_memory_map[0xa0].write16 = m68k_unused_16_w;
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zstate = 0;
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/* Assume default bank is $000000-$007FFF */
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zbank = 0;
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@ -256,20 +256,16 @@ unsigned int gen_bankswitch_r(void)
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/*-----------------------------------------------------------------------
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Z80 Bus controller chip functions
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-----------------------------------------------------------------------*/
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void gen_zbusreq_w(unsigned int state, unsigned int cycles)
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void gen_zbusreq_w(unsigned int data, unsigned int cycles)
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{
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if (state) /* !ZBUSREQ asserted */
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if (data) /* !ZBUSREQ asserted */
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{
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/* if z80 was running, resynchronize with 68k */
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/* check if Z80 is going to be stopped */
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if (zstate == 1)
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z80_run(cycles);
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/* update Z80 bus status */
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zstate |= 2;
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/* check if Z80 reset is released */
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if (zstate & 1)
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{
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/* resynchronize with 68k */
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z80_run(cycles);
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/* enable 68k access to Z80 bus */
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_m68k_memory_map *base = &m68k_memory_map[0xa0];
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base->read8 = z80_read_byte;
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@ -277,42 +273,48 @@ void gen_zbusreq_w(unsigned int state, unsigned int cycles)
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base->write8 = z80_write_byte;
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base->write16 = z80_write_word;
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}
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/* update Z80 bus status */
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zstate |= 2;
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}
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else /* !ZBUSREQ released */
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{
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/* if z80 is restarted, resynchronize with 68k */
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/* check if Z80 is going to be restarted */
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if (zstate == 3)
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mcycles_z80 = cycles;
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{
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/* resynchronize with 68k */
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mcycles_z80 = cycles;
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/* disable 68k access to Z80 bus */
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_m68k_memory_map *base = &m68k_memory_map[0xa0];
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base->read8 = m68k_read_bus_8;
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base->read16 = m68k_read_bus_16;
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base->write8 = m68k_unused_8_w;
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base->write16 = m68k_unused_16_w;
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}
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/* update Z80 bus status */
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zstate &= 1;
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/* disable 68k access */
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_m68k_memory_map *base = &m68k_memory_map[0xa0];
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base->read8 = m68k_read_bus_8;
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base->read16 = m68k_read_bus_16;
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base->write8 = m68k_unused_8_w;
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base->write16 = m68k_unused_16_w;
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}
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}
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void gen_zreset_w(unsigned int state, unsigned int cycles)
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void gen_zreset_w(unsigned int data, unsigned int cycles)
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{
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/* detect !ZRESET transitions */
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if (state == (zstate & 1))
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return;
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if (state) /* !ZRESET released */
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if (data) /* !ZRESET released */
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{
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/* if z80 is restarted, resynchronize with 68k */
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if (!zstate)
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mcycles_z80 = cycles;
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/* update Z80 bus status */
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zstate |= 1;
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/* check if Z80 bus has been requested */
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if (zstate & 2)
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/* check if Z80 is going to be restarted */
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if (zstate == 0)
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{
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/* resynchronize with 68k */
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mcycles_z80 = cycles;
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/* reset Z80 & YM2612 */
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z80_reset();
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fm_reset(cycles);
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}
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/* check if 68k access to Z80 bus is granted */
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else if (zstate == 2)
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{
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/* enable 68k access to Z80 bus */
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_m68k_memory_map *base = &m68k_memory_map[0xa0];
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@ -321,33 +323,41 @@ void gen_zreset_w(unsigned int state, unsigned int cycles)
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base->write8 = z80_write_byte;
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base->write16 = z80_write_word;
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}
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/* update Z80 bus status */
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zstate |= 1;
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}
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else /* !ZRESET asserted */
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{
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/* if z80 was running, resynchronize with 68k */
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/* check if Z80 is going to be stopped */
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if (zstate == 1)
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{
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/* resynchronize with 68k */
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z80_run(cycles);
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/* reset Z80 & YM2612 */
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z80_reset();
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}
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/* check if 68k had access to Z80 bus */
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else if (zstate == 3)
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{
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/* disable 68k access to Z80 bus */
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_m68k_memory_map *base = &m68k_memory_map[0xa0];
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base->read8 = m68k_read_bus_8;
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base->read16 = m68k_read_bus_16;
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base->write8 = m68k_unused_8_w;
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base->write16 = m68k_unused_16_w;
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}
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/* stop YM2612 */
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fm_reset(cycles);
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/* update Z80 bus status */
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zstate &= 2;
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/* disable 68k access */
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_m68k_memory_map *base = &m68k_memory_map[0xa0];
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base->read8 = m68k_read_bus_8;
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base->read16 = m68k_read_bus_16;
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base->write8 = m68k_unused_8_w;
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base->write16 = m68k_unused_16_w;
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}
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}
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void gen_zbank_w (unsigned int state)
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void gen_zbank_w (unsigned int data)
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{
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zbank = ((zbank >> 1) | ((state & 1) << 23)) & 0xFF8000;
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zbank = ((zbank >> 1) | ((data & 1) << 23)) & 0xFF8000;
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}
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int z80_irq_callback (int param)
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