rockbox/apps/codecs/libgme/gb_apu.h
Andree Buschmann 012df14a5f 2nd part of FS#12176. Tempo setting migrated to fixed point for libgme.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@30274 a1c6a512-1295-4272-9138-f99709370657
2011-08-09 20:21:55 +00:00

85 lines
2.7 KiB
C

// Nintendo Game Boy sound hardware emulator with save state support
// Gb_Snd_Emu 0.1.4
#ifndef GB_APU_H
#define GB_APU_H
#include "gb_oscs.h"
// Clock rate sound hardware runs at
enum { clock_rate = 4194304 * GB_APU_OVERCLOCK };
// Registers are at io_addr to io_addr+io_size-1
enum { io_addr = 0xFF10 };
enum { io_size = 0x30 };
enum { regs_size = io_size + 0x10 };
enum gb_mode_t {
mode_dmg, // Game Boy monochrome
mode_cgb, // Game Boy Color
mode_agb // Game Boy Advance
};
// 0: Square 1, 1: Square 2, 2: Wave, 3: Noise
enum { osc_count = 4 }; // 0 <= chan < osc_count
struct Gb_Apu {
struct Gb_Osc* oscs [osc_count];
blip_time_t last_time; // time sound emulator has been run to
blip_time_t frame_period; // clocks between each frame sequencer step
double volume_;
bool reduce_clicks_;
struct Gb_Square square1;
struct Gb_Square square2;
struct Gb_Wave wave;
struct Gb_Noise noise;
blip_time_t frame_time; // time of next frame sequencer action
int frame_phase; // phase of next frame sequencer step
uint8_t regs [regs_size];// last values written to registers
// large objects after everything else
struct Blip_Synth synth;
};
// Basics
// Initializes apu
void Apu_init( struct Gb_Apu* this );
// Emulates to time t, then writes data to addr
void Apu_write_register( struct Gb_Apu* this, blip_time_t t, int addr, int data ) ICODE_ATTR;
// Emulates to time t, then subtracts t from the current time.
// OK if previous write call had time slightly after t.
void Apu_end_frame( struct Gb_Apu* this,blip_time_t t ) ICODE_ATTR;
// More features
// Emulates to time t, then reads from addr
int Apu_read_register( struct Gb_Apu* this, blip_time_t t, int addr ) ICODE_ATTR;
// Resets hardware to state after power, BEFORE boot ROM runs. Mode selects
// sound hardware. If agb_wave is true, enables AGB's extra wave features.
void Apu_reset( struct Gb_Apu* this, enum gb_mode_t mode, bool agb_wave );
// Same as set_output(), but for a particular channel
void Apu_set_output( struct Gb_Apu* this, int chan, struct Blip_Buffer* center,
struct Blip_Buffer* left, struct Blip_Buffer* right );
// Sets overall volume, where 1.0 is normal
void Apu_volume( struct Gb_Apu* this, double v );
// If true, reduces clicking by disabling DAC biasing. Note that this reduces
// emulation accuracy, since the clicks are authentic.
void Apu_reduce_clicks( struct Gb_Apu* this, bool reduce );
// Sets frame sequencer rate, where 1.0 is normal. Meant for adjusting the
// tempo in a music player.
void Apu_set_tempo( struct Gb_Apu* this, int t );
void write_osc( struct Gb_Apu* this, int reg, int old_data, int data ) ICODE_ATTR;
#endif