diff options
Diffstat (limited to 'plugins/gme/game-music-emu-0.6pre/gme/Sap_Core.cpp')
| -rw-r--r-- | plugins/gme/game-music-emu-0.6pre/gme/Sap_Core.cpp | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/plugins/gme/game-music-emu-0.6pre/gme/Sap_Core.cpp b/plugins/gme/game-music-emu-0.6pre/gme/Sap_Core.cpp new file mode 100644 index 00000000..fa132458 --- /dev/null +++ b/plugins/gme/game-music-emu-0.6pre/gme/Sap_Core.cpp @@ -0,0 +1,192 @@ +// Game_Music_Emu 0.6-pre. http://www.slack.net/~ant/ + +#include "Sap_Core.h" + +/* Copyright (C) 2006-2008 Shay Green. This module is free software; you +can redistribute it and/or modify it under the terms of the GNU Lesser +General Public License as published by the Free Software Foundation; either +version 2.1 of the License, or (at your option) any later version. This +module is distributed in the hope that it will be useful, but WITHOUT ANY +WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS +FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more +details. You should have received a copy of the GNU Lesser General Public +License along with this module; if not, write to the Free Software Foundation, +Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ + +#include "blargg_source.h" + +int const idle_addr = 0xD2D2; + +Sap_Core::Sap_Core() +{ + set_tempo( 1 ); +} + +void Sap_Core::push( int b ) +{ + mem.ram [0x100 + cpu.r.sp--] = (byte) b; +} + +void Sap_Core::jsr_then_stop( addr_t addr ) +{ + cpu.r.pc = addr; + + // Some rips pop three bytes off stack before RTS. + push( (idle_addr - 1) >> 8 ); + push( idle_addr - 1 ); + + // 3 bytes so that RTI or RTS will jump to idle_addr. + // RTI will use the first two bytes as the address, 0xD2D2. + // RTS will use the last two bytes, 0xD2D1, which it internally increments. + push( (idle_addr - 1) >> 8 ); + push( (idle_addr - 1) >> 8 ); + push( idle_addr - 1 ); +} + +// Runs routine and allows it up to one second to return +void Sap_Core::run_routine( addr_t addr ) +{ + jsr_then_stop( addr ); + run_cpu( lines_per_frame * base_scanline_period * 60 ); + check( cpu.r.pc == idle_addr ); + check( cpu.r.sp >= 0xFF - 6 ); +} + +inline void Sap_Core::call_init( int track ) +{ + cpu.r.a = track; + + switch ( info.type ) + { + case 'B': + run_routine( info.init_addr ); + break; + + case 'C': + cpu.r.a = 0x70; + cpu.r.x = info.music_addr&0xFF; + cpu.r.y = info.music_addr >> 8; + run_routine( info.play_addr + 3 ); + cpu.r.a = 0; + cpu.r.x = track; + run_routine( info.play_addr + 3 ); + break; + + case 'D': + check( info.fastplay == lines_per_frame ); + jsr_then_stop( info.init_addr ); + break; + } +} + +void Sap_Core::setup_ram() +{ + memset( &mem, 0, sizeof mem ); + + ram() [idle_addr] = cpu.halt_opcode; + + addr_t const irq_addr = idle_addr - 1; + ram() [irq_addr] = cpu.halt_opcode; + ram() [0xFFFE] = (byte) irq_addr; + ram() [0xFFFF] = irq_addr >> 8; +} + +blargg_err_t Sap_Core::start_track( int track, info_t const& new_info ) +{ + info = new_info; + + check( ram() [idle_addr] == cpu.halt_opcode ); + + apu_ .reset( &apu_impl_ ); + apu2_.reset( &apu_impl_ ); + + cpu.reset( ram() ); + + frame_start = 0; + next_play = play_period() * 4; + saved_state.pc = idle_addr; + + time_mask = 0; // disables sound during init + call_init( track ); + time_mask = ~0; + + return blargg_ok; +} + +blargg_err_t Sap_Core::run_until( time_t end ) +{ + while ( cpu.time() < end ) + { + time_t next = min( next_play, end ); + if ( (run_cpu( next ) && cpu.r.pc != idle_addr) || cpu.error_count() ) + // TODO: better error + return BLARGG_ERR( BLARGG_ERR_GENERIC, "Emulation error (illegal instruction)" ); + + if ( cpu.r.pc == idle_addr ) + { + if ( saved_state.pc == idle_addr ) + { + // no code to run until next play call + cpu.set_time( next ); + } + else + { + // play had interrupted non-returning init, so restore registers + // init routine was running + check( cpu.r.sp == saved_state.sp - 3 ); + cpu.r = saved_state; + saved_state.pc = idle_addr; + } + } + + if ( cpu.time() >= next_play ) + { + next_play += play_period(); + + if ( cpu.r.pc == idle_addr || info.type == 'D' ) + { + // Save state if init routine is still running + if ( cpu.r.pc != idle_addr ) + { + check( info.type == 'D' ); + check( saved_state.pc == idle_addr ); + saved_state = cpu.r; + } + + addr_t addr = info.play_addr; + if ( info.type == 'C' ) + addr += 6; + jsr_then_stop( addr ); + } + else + { + dprintf( "init/play hadn't returned before next play call\n" ); + } + } + } + return blargg_ok; +} + +blargg_err_t Sap_Core::end_frame( time_t end ) +{ + RETURN_ERR( run_until( end ) ); + + cpu.adjust_time( -end ); + + time_t frame_time = lines_per_frame * scanline_period; + while ( frame_start < end ) + frame_start += frame_time; + frame_start -= end + frame_time; + + if ( (next_play -= end) < 0 ) + { + next_play = 0; + check( false ); + } + + apu_.end_frame( end ); + if ( info.stereo ) + apu2_.end_frame( end ); + + return blargg_ok; +} |