diff options
Diffstat (limited to 'src/mame/drivers/mac128.cpp')
-rw-r--r-- | src/mame/drivers/mac128.cpp | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/src/mame/drivers/mac128.cpp b/src/mame/drivers/mac128.cpp index 6abd0a12e8a..be754fb772f 100644 --- a/src/mame/drivers/mac128.cpp +++ b/src/mame/drivers/mac128.cpp @@ -194,6 +194,7 @@ private: uint16_t ram_600000_r(offs_t offset); void ram_600000_w(offs_t offset, uint16_t data, uint16_t mem_mask = ~ 0); void via_sync(); + void via_sync_end(); uint16_t mac_via_r(offs_t offset); void mac_via_w(offs_t offset, uint16_t data); uint16_t mac_autovector_r(offs_t offset); @@ -692,13 +693,21 @@ void mac128_state::via_sync() // is synced on that clock, so that's at a multiple of 10 in // absolute time - // - 4 cycles later E goes down and that's the end of the access + // - 4 cycles later E goes down and that's the end of the access, + + // We sync on the start of cycle (so that the via timings go ok) + // then on the end on via_sync_end() uint64_t cur_cycle = m_maincpu->total_cycles(); uint64_t vpa_cycle = cur_cycle+2; uint64_t via_start_cycle = (vpa_cycle + 9) / 10; - uint64_t end_cycle = via_start_cycle * 10 + 4; - m_maincpu->adjust_icount(cur_cycle - end_cycle + 4); // 4 cycles already counted by the core + uint64_t m68k_start_cycle = via_start_cycle * 10; + m_maincpu->adjust_icount(cur_cycle - m68k_start_cycle); // 4 cycles already counted by the core +} + +void mac128_state::via_sync_end() +{ + m_maincpu->adjust_icount(-4); } uint16_t mac128_state::mac_via_r(offs_t offset) @@ -712,6 +721,7 @@ uint16_t mac128_state::mac_via_r(offs_t offset) data = m_via->read(offset); + via_sync_end(); return (data & 0xff) | (data << 8); } @@ -723,6 +733,8 @@ void mac128_state::mac_via_w(offs_t offset, uint16_t data) via_sync(); m_via->write(offset, (data >> 8) & 0xff); + + via_sync_end(); } void mac128_state::mac_autovector_w(offs_t offset, uint16_t data) |