diff options
Diffstat (limited to 'c/echo.c')
| -rw-r--r-- | c/echo.c | 139 |
1 files changed, 134 insertions, 5 deletions
@@ -15,9 +15,37 @@ static volatile uint16_t* const z80_reset = (uint16_t *) 0xA11200; { *z80_busreq = 0; } #define Z80_RESET() \ { *z80_reset = 0; \ - int16_t i; for (i = 8; i >= 0; i--); \ + volatile int16_t i; for (i = 4; i >= 0; i--); \ *z80_reset = 0x100; } +// Macro to add delays +// Using volatile is needlessly ugly but at least portable +// GCC is already awful at optimizing, so this isn't that bad... +#define DELAY() \ + { volatile int16_t i; for (i = 0xFF; i >= 0; i--); } + +// Look-up tables for echo_set_volume +static const uint8_t fm_volumes[] = { + 0x7F,0x7B,0x77,0x73,0x70,0x6C,0x68,0x65, + 0x61,0x5E,0x5A,0x57,0x54,0x50,0x4D,0x4A, + 0x47,0x44,0x41,0x3F,0x3C,0x39,0x36,0x34, + 0x31,0x2F,0x2D,0x2A,0x28,0x26,0x24,0x22, + 0x20,0x1E,0x1C,0x1A,0x18,0x16,0x15,0x13, + 0x12,0x10,0x0F,0x0D,0x0C,0x0B,0x0A,0x09, + 0x08,0x07,0x06,0x05,0x04,0x04,0x03,0x02, + 0x02,0x01,0x01,0x01,0x00,0x00,0x00,0x00 +}; +static const uint8_t psg_volumes[] = { + 0x0F,0x0F,0x0E,0x0E,0x0D,0x0D,0x0C,0x0C, + 0x0B,0x0B,0x0B,0x0A,0x0A,0x0A,0x09,0x09, + 0x08,0x08,0x08,0x07,0x07,0x07,0x06,0x06, + 0x06,0x06,0x05,0x05,0x05,0x04,0x04,0x04, + 0x04,0x03,0x03,0x03,0x03,0x03,0x02,0x02, + 0x02,0x02,0x02,0x02,0x01,0x01,0x01,0x01, + 0x01,0x01,0x01,0x01,0x01,0x00,0x00,0x00, + 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 +}; + //*************************************************************************** // echo_init // Initializes Echo and gets it running. @@ -35,6 +63,9 @@ void echo_init(const void **list) { // due to linker shenanigans) z80_ram[0x1FFF] = 0x00; + // Direct stream is empty yet + z80_ram[0x1F00] = 0xFF; + // Load the instrument list manually, since thanks to linker shenanigans // we can't implement the list properly in ROM :/ volatile uint8_t *dest = &z80_ram[0x1C00]; @@ -65,6 +96,13 @@ void echo_init(const void **list) { while (count-- >= 0) *dest++ = *src++; + // Set up global volume + int i; + for (i = 0; i < 12; i++) + z80_ram[0x1FE0+i] = 0; + z80_ram[0x1FEC] = 1; + z80_ram[0x1FF1] = 1; + // Let Echo start running! Z80_RESET(); Z80_RELEASE(); @@ -84,8 +122,7 @@ void echo_send_command(uint8_t cmd) { // Is Echo busy yet? while (z80_ram[0x1FFF] != 0x00) { Z80_RELEASE(); - int16_t i; - for (i = 0x3FF; i >= 0; i--); + DELAY(); Z80_REQUEST(); } @@ -116,8 +153,7 @@ void echo_send_command_addr(uint8_t cmd, const void *addr) { // Is Echo busy yet? while (z80_ram[0x1FFF] != 0x00) { Z80_RELEASE(); - int16_t i; - for (i = 0x3FF; i >= 0; i--); + DELAY(); Z80_REQUEST(); } @@ -187,9 +223,11 @@ void echo_stop_bgm(void) { // Resumes background music playback. //*************************************************************************** +/* void echo_resume_bgm(void) { echo_send_command(ECHO_CMD_RESUMEBGM); } +*/ //*************************************************************************** // echo_play_sfx @@ -212,6 +250,95 @@ void echo_stop_sfx(void) { } //*************************************************************************** +// echo_play_direct +// Injects events into the BGM stream for the next tick. +//--------------------------------------------------------------------------- +// param ptr: pointer to BGM stream +//*************************************************************************** + +void echo_play_direct(const void *ptr) { + // We need access to Z80 bus + Z80_REQUEST(); + + // Check where we can start writing events + volatile uint8_t *dest = &z80_ram[0x1F00]; + while (*dest != 0xFF) dest++; + + // Write the events + const uint8_t *src = (uint8_t*)(ptr); + for (;;) { + uint8_t byte = *src++; + *dest++ = byte; + if (byte == 0xFF) break; + } + + // Done with the Z80 + Z80_RELEASE(); +} + +//*************************************************************************** +// echo_set_volume +// Changes the global volume for every channel. +//--------------------------------------------------------------------------- +// param vol: new volume (0 = quietest, 255 = loudest) +//*************************************************************************** + +void echo_set_volume(uint8_t vol) { + // We need access to Z80 bus + Z80_REQUEST(); + + // Set FM volume values + uint8_t fm_vol = fm_volumes[vol >> 2]; + z80_ram[0x1FE0] = fm_vol; + z80_ram[0x1FE1] = fm_vol; + z80_ram[0x1FE2] = fm_vol; + z80_ram[0x1FE3] = fm_vol; + z80_ram[0x1FE4] = fm_vol; + z80_ram[0x1FE5] = fm_vol; + z80_ram[0x1FE6] = fm_vol; + z80_ram[0x1FE7] = fm_vol; + + // Set PSG volume values + uint8_t psg_vol = psg_volumes[vol >> 2]; + z80_ram[0x1FE8] = psg_vol; + z80_ram[0x1FE9] = psg_vol; + z80_ram[0x1FEA] = psg_vol; + z80_ram[0x1FEB] = psg_vol; + + // Determine whether to enable PCM + z80_ram[0x1FEC] = (vol >= 0x40) ? 1 : 0; + + // Tell Echo to update all the volumes + z80_ram[0x1FF1] = 1; + + // Done with the Z80 + Z80_RELEASE(); +} + +//*************************************************************************** +// echo_set_volume_ex +// Changes the global volume for each individual channel. +//--------------------------------------------------------------------------- +// param ptr: pointer to array with volume values +//*************************************************************************** + +void echo_set_volume_ex(const uint8_t *ptr) { + // We need access to Z80 bus + Z80_REQUEST(); + + // Store the new volume values + int i; + for (i = 0; i < 13; i++) + z80_ram[0x1FE0+i] = ptr[i]; + + // Tell Echo to update all the volumes + z80_ram[0x1FF1] = 1; + + // Done with the Z80 + Z80_RELEASE(); +} + +//*************************************************************************** // echo_set_pcm_rate // Changes the playback rate of PCM. //--------------------------------------------------------------------------- @@ -238,6 +365,8 @@ uint16_t echo_get_status(void) { status = z80_ram[0x1FF0]; if (z80_ram[0x1FFF] != 0) status |= ECHO_STAT_BUSY; + if (z80_ram[0x1F00] != 0xFF) + status |= ECHO_STAT_DIRBUSY; // Done with the Z80 Z80_RELEASE(); |