Merge pull request #545 from khokh2001/opl3_mode

opl: Add OPL3 mode.

The DMX library had limited support for the features of the OPL3 chip,
enabled by setting the DMXOPTIONS variable. This reproduces the OPL3 
support in Chocolate Doom's OPL playback and emulation layer.

Huge thanks to Alexey Khokholov for researching and developing this. 
This fixes #470.

1 files changed, 4 insertions, 2 deletions

diff --git a/opl/opl.h b/opl/opl.h
index c4b91b25..c4bc2c80 100644
--- a/opl/opl.h
+++ b/opl/opl.h
@@ -26,7 +26,8 @@ typedef void (*opl_callback_t)(void *data);
 typedef enum
 {
     OPL_REGISTER_PORT = 0,
-    OPL_DATA_PORT = 1
+    OPL_DATA_PORT = 1,
+    OPL_REGISTER_PORT_OPL3 = 2
 } opl_port_t;
 
 #define OPL_NUM_OPERATORS   21
@@ -37,6 +38,7 @@ typedef enum
 #define OPL_REG_TIMER2            0x03
 #define OPL_REG_TIMER_CTRL        0x04
 #define OPL_REG_FM_MODE           0x08
+#define OPL_REG_NEW               0x105
 
 // Operator registers (21 of each):
 
@@ -101,7 +103,7 @@ int OPL_Detect(void);
 
 // Initialize all registers, performed on startup.
 
-void OPL_InitRegisters(void);
+void OPL_InitRegisters(int opl3);
 
 //
 // Timer callback functions.