Split off AD1848 CODEC from main Windows Sound System emulation.

src/sound_ad1848.h

@@ -0,0 +1,27 @@
+typedef struct ad1848_t
+{
+        int index;
+        uint8_t regs[16];
+        uint8_t status;
+        
+        int trd;
+        int mce;
+        
+        int count;
+        
+        int16_t out_l, out_r;
+        
+        int interp_count, inc;
+
+        int enable;
+
+        int irq, dma;
+} ad1848_t;
+
+void ad1848_setirq(ad1848_t *ad1848, int irq);
+void ad1848_setdma(ad1848_t *ad1848, int dma);
+
+uint8_t ad1848_read(uint16_t addr, void *p);
+void ad1848_write(uint16_t addr, uint8_t val, void *p);
+
+void ad1848_poll(void *p, int16_t *l, int16_t *r);