diff options
Diffstat (limited to 'opl')
| -rw-r--r-- | opl/examples/droplay.c | 31 | ||||
| -rw-r--r-- | opl/opl.c | 244 | ||||
| -rw-r--r-- | opl/opl.h | 31 | ||||
| -rw-r--r-- | opl/opl_obsd.c | 2 |
4 files changed, 269 insertions, 39 deletions
diff --git a/opl/examples/droplay.c b/opl/examples/droplay.c index d53a427b..36f5c3c0 100644 --- a/opl/examples/droplay.c +++ b/opl/examples/droplay.c @@ -73,30 +73,6 @@ void ClearAllRegs(void) } } -// Detect an OPL chip. - -int DetectOPL(void) -{ - int val1, val2; - - WriteReg(OPL_REG_TIMER_CTRL, 0x60); - WriteReg(OPL_REG_TIMER_CTRL, 0x80); - - val1 = OPL_ReadPort(OPL_REGISTER_PORT) & 0xe0; - - WriteReg(OPL_REG_TIMER1, 0xff); - WriteReg(OPL_REG_TIMER_CTRL, 0x21); - - OPL_Delay(1); - - val2 = OPL_ReadPort(OPL_REGISTER_PORT) & 0xe0; - - WriteReg(OPL_REG_TIMER_CTRL, 0x60); - WriteReg(OPL_REG_TIMER_CTRL, 0x80); - - return val1 == 0 && val2 == 0xc0; -} - void Init(void) { if (SDL_Init(SDL_INIT_TIMER) < 0) @@ -110,12 +86,6 @@ void Init(void) fprintf(stderr, "Unable to initialise OPL layer\n"); exit(-1); } - - if (!DetectOPL()) - { - fprintf(stderr, "Adlib not detected\n"); - exit(-1); - } } void Shutdown(void) @@ -236,7 +206,6 @@ int main(int argc, char *argv[]) } Init(); - ClearAllRegs(); PlayFile(argv[1]); @@ -1,4 +1,4 @@ -// Emacs style mode select -*- C++ -*- +// Emacs style mode select -*- C++ -*- //----------------------------------------------------------------------------- // // Copyright(C) 2009 Simon Howard @@ -28,6 +28,10 @@ #include <stdio.h> #include <stdlib.h> +#ifdef _WIN32_WCE +#include "libc_wince.h" +#endif + #include "SDL.h" #include "opl.h" @@ -56,25 +60,113 @@ static opl_driver_t *drivers[] = }; static opl_driver_t *driver = NULL; +static int init_stage_reg_writes = 1; -int OPL_Init(unsigned int port_base) +// +// Init/shutdown code. +// + +// Initialize the specified driver and detect an OPL chip. Returns +// true if an OPL is detected. + +static int InitDriver(opl_driver_t *_driver, unsigned int port_base) { - int i; + // Initialize the driver. + + if (!_driver->init_func(port_base)) + { + return 0; + } + + // The driver was initialized okay, so we now have somewhere + // to write to. It doesn't mean there's an OPL chip there, + // though. Perform the detection sequence to make sure. + // (it's done twice, like how Doom does it). + + driver = _driver; + init_stage_reg_writes = 1; + + if (!OPL_Detect() || !OPL_Detect()) + { + printf("OPL_Init: No OPL detected using '%s' driver.\n", _driver->name); + _driver->shutdown_func(); + driver = NULL; + return 0; + } - // Try drivers until we find a working one: + // Initialize all registers. + + OPL_InitRegisters(); + + init_stage_reg_writes = 0; + + printf("OPL_Init: Using driver '%s'.\n", driver->name); + + return 1; +} + +// Find a driver automatically by trying each in the list. + +static int AutoSelectDriver(unsigned int port_base) +{ + int i; for (i=0; drivers[i] != NULL; ++i) { - if (drivers[i]->init_func(port_base)) + if (InitDriver(drivers[i], port_base)) { - driver = drivers[i]; return 1; } } + printf("OPL_Init: Failed to find a working driver.\n"); + return 0; } +// Initialize the OPL library. Returns true if initialized +// successfully. + +int OPL_Init(unsigned int port_base) +{ + char *driver_name; + int i; + + driver_name = getenv("OPL_DRIVER"); + + if (driver_name != NULL) + { + // Search the list until we find the driver with this name. + + for (i=0; drivers[i] != NULL; ++i) + { + if (!strcmp(driver_name, drivers[i]->name)) + { + if (InitDriver(drivers[i], port_base)) + { + return 1; + } + else + { + printf("OPL_Init: Failed to initialize " + "driver: '%s'.\n", driver_name); + return 0; + } + } + } + + printf("OPL_Init: unknown driver: '%s'.\n", driver_name); + + return 0; + } + else + { + return AutoSelectDriver(port_base); + } +} + +// Shut down the OPL library. + void OPL_Shutdown(void) { if (driver != NULL) @@ -115,6 +207,146 @@ unsigned int OPL_ReadPort(opl_port_t port) } } +// +// Higher-level functions, based on the lower-level functions above +// (register write, etc). +// + +unsigned int OPL_ReadStatus(void) +{ + return OPL_ReadPort(OPL_REGISTER_PORT); +} + +// Write an OPL register value + +void OPL_WriteRegister(int reg, int value) +{ + int i; + + OPL_WritePort(OPL_REGISTER_PORT, reg); + + // For timing, read the register port six times after writing the + // register number to cause the appropriate delay + + for (i=0; i<6; ++i) + { + // An oddity of the Doom OPL code: at startup initialisation, + // the spacing here is performed by reading from the register + // port; after initialisation, the data port is read, instead. + + if (init_stage_reg_writes) + { + OPL_ReadPort(OPL_REGISTER_PORT); + } + else + { + OPL_ReadPort(OPL_DATA_PORT); + } + } + + OPL_WritePort(OPL_DATA_PORT, value); + + // Read the register port 24 times after writing the value to + // cause the appropriate delay + + for (i=0; i<24; ++i) + { + OPL_ReadStatus(); + } +} + +// Detect the presence of an OPL chip + +int OPL_Detect(void) +{ + int result1, result2; + int i; + + // Reset both timers: + OPL_WriteRegister(OPL_REG_TIMER_CTRL, 0x60); + + // Enable interrupts: + OPL_WriteRegister(OPL_REG_TIMER_CTRL, 0x80); + + // Read status + result1 = OPL_ReadStatus(); + + // Set timer: + OPL_WriteRegister(OPL_REG_TIMER1, 0xff); + + // Start timer 1: + OPL_WriteRegister(OPL_REG_TIMER_CTRL, 0x21); + + // Wait for 80 microseconds + // This is how Doom does it: + + for (i=0; i<200; ++i) + { + OPL_ReadStatus(); + } + + OPL_Delay(1); + + // Read status + result2 = OPL_ReadStatus(); + + // Reset both timers: + OPL_WriteRegister(OPL_REG_TIMER_CTRL, 0x60); + + // Enable interrupts: + OPL_WriteRegister(OPL_REG_TIMER_CTRL, 0x80); + + return (result1 & 0xe0) == 0x00 + && (result2 & 0xe0) == 0xc0; +} + +// Initialize registers on startup + +void OPL_InitRegisters(void) +{ + int r; + + // Initialize level registers + + for (r=OPL_REGS_LEVEL; r <= OPL_REGS_LEVEL + OPL_NUM_OPERATORS; ++r) + { + OPL_WriteRegister(r, 0x3f); + } + + // Initialize other registers + // These two loops write to registers that actually don't exist, + // but this is what Doom does ... + // Similarly, the <= is also intenational. + + for (r=OPL_REGS_ATTACK; r <= OPL_REGS_WAVEFORM + OPL_NUM_OPERATORS; ++r) + { + OPL_WriteRegister(r, 0x00); + } + + // More registers ... + + for (r=1; r < OPL_REGS_LEVEL; ++r) + { + OPL_WriteRegister(r, 0x00); + } + + // Re-initialize the low registers: + + // Reset both timers and enable interrupts: + OPL_WriteRegister(OPL_REG_TIMER_CTRL, 0x60); + OPL_WriteRegister(OPL_REG_TIMER_CTRL, 0x80); + + // "Allow FM chips to control the waveform of each operator": + OPL_WriteRegister(OPL_REG_WAVEFORM_ENABLE, 0x20); + + // Keyboard split point on (?) + OPL_WriteRegister(OPL_REG_FM_MODE, 0x40); +} + +// +// Timer functions. +// + void OPL_SetCallback(unsigned int ms, opl_callback_t callback, void *data) { if (driver != NULL) @@ -58,7 +58,11 @@ typedef enum #define OPL_REGS_FREQ_2 0xB0 #define OPL_REGS_FEEDBACK 0xC0 -// Initialise the OPL subsystem. +// +// Low-level functions. +// + +// Initialize the OPL subsystem. int OPL_Init(unsigned int port_base); @@ -74,6 +78,31 @@ void OPL_WritePort(opl_port_t port, unsigned int value); unsigned int OPL_ReadPort(opl_port_t port); +// +// Higher-level functions. +// + +// Read the cuurrent status byte of the OPL chip. + +unsigned int OPL_ReadStatus(void); + +// Write to an OPL register. + +void OPL_WriteRegister(int reg, int value); + +// Perform a detection sequence to determine that an +// OPL chip is present. + +int OPL_Detect(void); + +// Initialize all registers, performed on startup. + +void OPL_InitRegisters(void); + +// +// Timer callback functions. +// + // Set a timer callback. After the specified number of milliseconds // have elapsed, the callback will be invoked. diff --git a/opl/opl_obsd.c b/opl/opl_obsd.c index a3a22ab8..82d9186d 100644 --- a/opl/opl_obsd.c +++ b/opl/opl_obsd.c @@ -101,5 +101,5 @@ opl_driver_t opl_openbsd_driver = OPL_Timer_SetPaused }; -#endif /* #ifdef HAVE_IOPERM */ +#endif /* #ifdef HAVE_LIBI386 */ |