Support for multi-packet SGB commands

Core/gb.h

@@ -469,10 +469,11 @@ struct GB_gameboy_internal_s {
     
     /* Super Game Boy state, only dumped/loaded for relevant models */
     GB_SECTION(sgb,
-        uint8_t sgb_command[16];
+        uint8_t sgb_command[16 * 7];
-        uint8_t sgb_command_write_index;
+        uint16_t sgb_command_write_index;
         bool sgb_ready_for_pulse;
         bool sgb_ready_for_write;
+        bool sgb_ready_for_stop;
         bool sgb_disable_commands;
         /* Multiplayer Input */
         uint8_t sgb_player_count, sgb_current_player;

Core/sgb.c

@@ -4,6 +4,8 @@ enum {
     MLT_REQ = 0x11,
 };
 
+#define SGB_PACKET_SIZE 16
+
 static void command_ready(GB_gameboy_t *gb)
 {
     /* SGB header commands are used to send the contents of the header to the SNES CPU.
@@ -12,7 +14,8 @@ static void command_ready(GB_gameboy_t *gb)
        Checksum: Simple one byte sum for the following content bytes
        0xE content bytes. The last command, FB, is padded with zeros, so information past the header is not sent. */
     
-    if (gb->sgb_command[0] >= 0xF0) {
+    
+    if ((gb->sgb_command[0] & 0xF1) == 0xF1) {
         uint8_t checksum = 0;
         for (unsigned i = 2; i < 0x10; i++) {
             checksum += gb->sgb_command[i];
@@ -22,7 +25,6 @@ static void command_ready(GB_gameboy_t *gb)
             gb->sgb_disable_commands = true;
             return;
         }
-    }
         if (gb->sgb_command[0] == 0xf9) {
             if (gb->sgb_command[0xc] != 3) { // SGB Flag
                 GB_log(gb, "SGB flag is not 0x03, disabling SGB features\n");
@@ -35,12 +37,23 @@ static void command_ready(GB_gameboy_t *gb)
                 gb->sgb_disable_commands = true;
             }
         }
+        return;
+    }
+    
 
     switch (gb->sgb_command[0] >> 3) {
         case MLT_REQ:
             gb->sgb_player_count = (uint8_t[]){1, 2, 1, 4}[gb->sgb_command[1] & 3];
             gb->sgb_current_player = gb->sgb_player_count - 1;
             break;
+        default:
+            GB_log(gb, "Unimplemented SGB command %x: ", gb->sgb_command[0] >> 3);
+            for (unsigned i = 0; i < gb->sgb_command_write_index / 8; i++) {
+                GB_log(gb, "%02x ", gb->sgb_command[i]);
+            }
+            GB_log(gb, "\n");
+            ;
+
     }
 }
 
@@ -48,6 +61,12 @@ void GB_sgb_write(GB_gameboy_t *gb, uint8_t value)
 {
     if (!GB_is_sgb(gb)) return;
     if (gb->sgb_disable_commands) return;
+    if (gb->sgb_command_write_index >= sizeof(gb->sgb_command) * 8) return;
+    
+    uint16_t command_size = (gb->sgb_command[0] & 7 ?: 1) * SGB_PACKET_SIZE * 8;
+    if ((gb->sgb_command[0] & 0xF1) == 0xF1) {
+        command_size = SGB_PACKET_SIZE * 8;
+    }
     
     switch ((value >> 4) & 3) {
         case 3:
@@ -56,35 +75,48 @@ void GB_sgb_write(GB_gameboy_t *gb, uint8_t value)
             
         case 2: // Zero
             if (!gb->sgb_ready_for_pulse || !gb->sgb_ready_for_write) return;
-            if (gb->sgb_command_write_index >= sizeof(gb->sgb_command) * 8) {
+            if (gb->sgb_ready_for_stop) {
+                if (gb->sgb_command_write_index == command_size) {
                     command_ready(gb);
+                    gb->sgb_command_write_index = 0;
+                    memset(gb->sgb_command, 0, sizeof(gb->sgb_command));
+                }
                 gb->sgb_ready_for_pulse = false;
                 gb->sgb_ready_for_write = false;
+                gb->sgb_ready_for_stop = false;
             }
             else {
                 gb->sgb_command_write_index++;
                 gb->sgb_ready_for_pulse = false;
+                if (((gb->sgb_command_write_index) & (SGB_PACKET_SIZE * 8 - 1)) == 0) {
+                    gb->sgb_ready_for_stop = true;
+                }
             }
             break;
         case 1: // One
             if (!gb->sgb_ready_for_pulse || !gb->sgb_ready_for_write) return;
-            if (gb->sgb_command_write_index >= sizeof(gb->sgb_command) * 8) {
+            if (gb->sgb_ready_for_stop) {
                 GB_log(gb, "Corrupt SGB command.\n");
                 gb->sgb_ready_for_pulse = false;
                 gb->sgb_ready_for_write = false;
+                gb->sgb_command_write_index = 0;
+                memset(gb->sgb_command, 0, sizeof(gb->sgb_command));
             }
             else {
                 gb->sgb_command[gb->sgb_command_write_index / 8] |= 1 << (gb->sgb_command_write_index & 7);
                 gb->sgb_command_write_index++;
                 gb->sgb_ready_for_pulse = false;
+                if (((gb->sgb_command_write_index) & (SGB_PACKET_SIZE * 8 - 1)) == 0) {
+                    gb->sgb_ready_for_stop = true;
+                }
             }
             break;
         
         case 0:
+            if (!gb->sgb_ready_for_pulse) return;
             gb->sgb_ready_for_pulse = false;
             gb->sgb_ready_for_write = true;
-            gb->sgb_command_write_index = 0;
+            gb->sgb_ready_for_pulse = false;
-            memset(gb->sgb_command, 0, sizeof(gb->sgb_command));
             if (gb->sgb_player_count > 1 && (value & 0x30) != (gb->io_registers[GB_IO_JOYP] & 0x30)) {
                 gb->sgb_current_player++;
                 gb->sgb_current_player &= gb->sgb_player_count - 1;