ZX 128K MIDI port emulation (but no output).

Makefile

@@ -22,8 +22,10 @@ sources_generic = \
     fileutil.c \
     gzx.c \
     memio.c \
+    midi.c \
     z80.c \
     z80dep.c \
+    rs232.c \
     snap.c \
     snap_ay.c \
     strutil.c \

ay.c

@@ -5,7 +5,6 @@
 
 #include <assert.h>
 #include <stdint.h>
-#include <stdio.h>
 #include <stdlib.h>
 #include "ay.h"
 
@@ -50,6 +49,17 @@ static void reset_env_gen(ay_t *ay)
 	}
 }
 
+/** Write AY I/O port.
+ *
+ * @param ay AY
+ * @param val Value
+ */
+static void ay_io_port_write(ay_t *ay, uint8_t val)
+{
+	if (ay->ioport_write != NULL)
+		ay->ioport_write(ay->ioport_write_arg, val);
+}
+
 /** Write AY register.
  *
  * @param ay AY
@@ -59,10 +69,10 @@ void ay_reg_write(ay_t *ay, uint8_t val)
 {
 	switch (ay->cur_reg) {
 	case ay_rn_esccr: reset_env_gen(ay); break;
+	case ay_rn_io_a: ay_io_port_write(ay, val); break;
 	}
 
 	ay->reg[ay->cur_reg] = val;
-//	printf("ay_reg_write %d,0x%02x\n", ay->cur_reg, val);
 }
 
 /** Read currently selected AY register.

ay.h

@@ -58,6 +58,9 @@ typedef struct {
 	uint16_t noise_cnt;
 	uint8_t  noise_smp;
 	uint32_t d_clocks;
+
+	void (*ioport_write)(void *, uint8_t);
+	void *ioport_write_arg;
 } ay_t;
 
 extern void ay_reg_select(ay_t *, uint8_t);

clock.h

@@ -2,5 +2,6 @@
 #define CLOCK_H
 
 #define Z80_CLOCK 3500000L
+#define MIDI_BAUD 31250
 
 #endif

gzx.c

@@ -14,6 +14,7 @@
 #include <ctype.h>
 #include <string.h>
 #include <time.h>
+#include "clock.h"
 #include "intdef.h"
 #include "memio.h"
 #include "mgfx.h"
@@ -22,11 +23,13 @@
 #include "z80.h"
 #include "zx_kbd.h"
 #include "zx_scr.h"
+#include "rs232.h"
 #include "snap.h"
 #include "zx_sound.h"
 #include "zx_tape.h"
 #include "ay.h"
 #include "menus.h"
+#include "midi.h"
 #include "debug.h"
 #include "z80g.h"
 #include "zx.h"
@@ -220,6 +223,22 @@ void zx_scr_save(void) {
   fclose(f);
 }
 
+/** Value was written to AY I/O port.
+ *
+ * @param arg Callback argument
+ * @param val Value
+ */
+static void gzx_ay_ioport_write(void *arg, uint8_t val)
+{
+	rs232_write(&rs232, val);
+}
+
+/** Character was sent via RS-232 port */
+static void gzx_rs232_sendchar(void *arg, uint8_t val)
+{
+	midi_port_write(&midi, val);
+}
+
 static unsigned long snd_t,tapp_t;
 
 void zx_reset(void) {
@@ -263,8 +282,16 @@ static int zx_init(void) {
   if(zx_keys_init()<0) return -1;
   printf("sound\n");
   if(zx_sound_init()<0) return -1;
+
   printf("ay\n");
   if(ay_init(&ay0, 125/*d_t_states*/)<0) return -1;
+  ay0.ioport_write = gzx_ay_ioport_write;
+  ay0.ioport_write_arg = &ay0;
+
+  rs232_init(&rs232, Z80_CLOCK / MIDI_BAUD);
+  rs232.sendchar = gzx_rs232_sendchar;
+  rs232.sendchar_arg = &rs232;
+
   if(zx_tape_init(79)<0) return -1;
   //if(zx_tape_selectfile("/mnt/dos/jetpac.tap")<0) return -1;
 

midi.c

@@ -0,0 +1,15 @@
+/*
+ * GZX - George's ZX Spectrum Emulator
+ * ZX Spectrum 128K MIDI port emulation
+ */
+#include <stdio.h>
+#include "midi.h"
+
+void midi_port_init(midi_port_t *mp)
+{
+}
+
+void midi_port_write(midi_port_t *mp, uint8_t val)
+{
+	printf("MIDI port write: 0x%02x\n", val);
+}

midi.h

@@ -0,0 +1,16 @@
+/*
+ * GZX - George's ZX Spectrum Emulator
+ * ZX Spectrum 128K MIDI port emulation
+ */
+#ifndef MIDI_PORT_H
+#define MIDI_PORT_H
+
+#include <stdint.h>
+
+typedef struct {
+} midi_port_t;
+
+extern void midi_port_init(midi_port_t *);
+extern void midi_port_write(midi_port_t *, uint8_t);
+
+#endif

rs232.c

@@ -0,0 +1,32 @@
+/*
+ * GZX - George's ZX Spectrum Emulator
+ * ZX Spectrum 128K RS-232 port emulation
+ */
+#include <stdio.h>
+#include "rs232.h"
+
+void rs232_init(rs232_t *rs, uint32_t d_clocks)
+{
+	rs->d_clocks = d_clocks;
+	rs->state = rs232_idle;
+}
+
+void rs232_write(rs232_t *rs, uint8_t val)
+{
+	uint8_t b;
+
+	b = (val >> rs232_txd) & 0x1;
+
+	if (rs->state == rs232_idle && (b == 0x0)) {
+		rs->state = rs232_sending;
+		rs->bit_no = 0;
+		rs->buf = 0x0;
+	} else if (rs->state == rs232_sending) {
+		rs->buf = (rs->buf >> 1) | (b << 7);
+		if (++rs->bit_no >= 8) {
+			rs->state = rs232_idle;
+			if (rs->sendchar != NULL)
+				rs->sendchar(rs->sendchar_arg, rs->buf);
+		}
+	}
+}

rs232.h

@@ -0,0 +1,38 @@
+/*
+ * GZX - George's ZX Spectrum Emulator
+ * ZX Spectrum 128K RS-232 port emulation
+ */
+#ifndef RS232_H
+#define RS232_H
+
+#include <stdint.h>
+
+/* Bits within the RS232 register */
+enum {
+	rs232_txd = 2
+};
+
+typedef enum {
+	rs232_idle,
+	rs232_sending
+} rs232_state_t;
+
+typedef struct {
+	/** Z80 T states between successive bits (rel. to baud rate) */
+	uint32_t d_clocks;
+	/** State */
+	rs232_state_t state;
+	/** Bit number */
+	uint8_t bit_no;
+	/** Transfer buffer */
+	uint8_t buf;
+	/** A symbol was sent */
+	void (*sendchar)(void *, uint8_t);
+	/** Argument to sendchar callback */
+	void *sendchar_arg;
+} rs232_t;
+
+extern void rs232_init(rs232_t *, uint32_t);
+extern void rs232_write(rs232_t *, uint8_t);
+
+#endif

zx.c

@@ -4,6 +4,14 @@
  */
 
 #include "ay.h"
+#include "rs232.h"
+#include "zx.h"
 
 /** First AY */
 ay_t ay0;
+
+/** MIDI port */
+midi_port_t midi;
+
+/** RS-232 port */
+rs232_t rs232;

zx.h

@@ -6,7 +6,11 @@
 #define ZX_H
 
 #include "ay.h"
+#include "midi.h"
+#include "rs232.h"
 
 extern ay_t ay0;
+extern midi_port_t midi;
+extern rs232_t rs232;
 
 #endif