Emulator: working decoding logic, outputting terminal to stdout

pat80-computer/software/z80-assembly/os/tests/out_single_char.asm

@@ -0,0 +1,7 @@
+; @language: Z80 ASM
+; Simple possible code test:
+; outputs a single character "A" on IO port 0, then halts
+
+ld a,'A'
+out (1),a
+halt

pat80-emulator/main.c

@@ -1,18 +1,19 @@
 #include <Z/constants/pointer.h> /* Z_NULL */
 #include <Z80.h>
 #include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
 
 #define CYCLES_PER_FRAME 69888
 #define CYCLES_AT_INT    24
 #define CYCLES_PER_INT   32
 #define ROM_SIZE         0x8000 /* 32 KiB */
-#define MEMORY_SIZE      0x8000 /* 32 KiB */
+#define MEMORY_SIZE      0xFFFF /* 64 KiB */
 
 typedef struct {
         void* context;
         zuint8 (* read)(void *context);
         void (* write)(void *context, zuint8 value);
-        zuint16 assigned_port;
 } Device;
 
 typedef struct {
@@ -24,49 +25,107 @@ typedef struct {
 } Machine;
 
 
-Device *machine_find_device(Machine *self, zuint16 port)
-        {
-        zusize index = 0;
-
-        for (; index < self->device_count; index++)
-                if (self->devices[index].assigned_port == port)
-                        return &self->devices[index];
-
-        return Z_NULL;
-        }
-
-
-static zuint8 machine_cpu_read(Machine *self, zuint16 address)
-        {
+static zuint8 machine_cpu_read(Machine *self, zuint16 address) {
         return address < MEMORY_SIZE ? self->memory[address] : 0xFF;
-        }
+}
 
 
-static void machine_cpu_write(Machine *self, zuint16 address, zuint8 value)
-        {
+static void machine_cpu_write(Machine *self, zuint16 address, zuint8 value) {
         if (address >= ROM_SIZE && address < MEMORY_SIZE)
                 self->memory[address] = value;
+}
+
+
+static zuint8 machine_cpu_in(Machine *self, zuint16 port) {
+	// Pat80 has 8 devices, decoded based on the 3 most significant IO addr bits.
+        // Note the Z80 has 16 bit address bus, but only the first 8 are used as IO addr,
+        // so the 3 most significant IO addr bits in this case are A7, A6, A5. The bits
+        // A4-A0 may be used by the single device, at its own discretion.
+        zuint16 bitmask = 7; // 0000000000000111
+        int decoded = port & bitmask;
+	if (decoded <= 0x1F) {
+		// Port 0 (0x00 to 0x1F): terminal
+		//printf("TERMINAL_READ");
+                //return 'H';
+                return 0x00;
         }
-
-
-static zuint8 machine_cpu_in(Machine *self, zuint16 port)
-        {
-        Device *device = machine_find_device(self, port);
-
-        return device != Z_NULL ? device->read(device->context) : 0xFF;
+        if (decoded <=  0x3F) {
+                // Port 1 (0x20 to 0x3F): sound card (sn76489)
+		printf("\nsound_cmd[IN]: Not supported!\n");
+                return 0x00;
         }
-
-
-static void machine_cpu_out(Machine *self, zuint16 port, zuint8 value)
-        {
-        Device *device = machine_find_device(self, port);
-
-        if (device != Z_NULL) device->write(device->context, value);
+        if (decoded <=  0x5F) {
+                // Port 2 (0x40 to 0x5F)
+                printf("IO_ERROR_IN: No device at port 2\n");
+                return 0x00;
         }
+        if (decoded <=  0x7F) {
+                // Port 3 (0x60 to 0x7F)
+                printf("IO_ERROR_IN: No device at port 3\n");
+                return 0x00;
+        }
+        if (decoded <=  0x9F) {
+                // Port 4 (0x80 to 0x9F)
+                printf("IO_ERROR_IN: No device at port 4\n");
+                return 0x00;
+        }
+        if (decoded <=  0x5F) {
+                // Port 5 (0xA0 to 0xBF)
+                printf("IO_ERROR_IN: No device at port 5\n");
+                return 0x00;
+        }
+        if (decoded <=  0x5F) {
+                // Port 6 (0xC0 to 0xDF)
+                printf("IO_ERROR_IN: No device at port 6\n");
+                return 0x00;
+        }
+        if (decoded <=  0x5F) {
+                // Port 7 (0xE0 to 0xFF)
+                printf("IO_ERROR_IN: No device at port 7\n");
+        } else {
+                printf("IO_ERROR_IN: Invalid port address: %#04x\n", port);
+        }
+}
 
 
-void machine_initialize(Machine *self)
-        {
+static void machine_cpu_out(Machine *self, zuint16 port, zuint8 value) {
+	// Pat80 has 8 devices, decoded based on the 3 most significant IO addr bits.
+        // Note the Z80 has 16 bit address bus, but only the first 8 are used as IO addr,
+        // so the 3 most significant IO addr bits in this case are A7, A6, A5. The bits
+        // A4-A0 may be used by the single device, at its own discretion.
+        zuint16 bitmask = 0xE0; // 0000000011100000
+        int decoded = port & bitmask;
+	if (decoded <= 0x1F) {
+		// Port 0 (0x00 to 0x1F): terminal
+		printf("%c", value);
+	} else if (decoded <= 0x3F) {
+                // Port 1 (0x20 to 0x3F): sound card (sn76489)
+		printf("\nsound_cmd[%#04x]\n", value);
+        } else if (decoded <= 0x5F) {
+                // Port 2 (0x40 to 0x5F)
+                printf("IO_ERROR_OUT: No device at port 2\n");
+        } else if (decoded <= 0x7F) {
+                // Port 3 (0x60 to 0x7F)
+                printf("IO_ERROR_OUT: No device at port 3\n");
+        } else if (decoded <= 0x9F) {
+                // Port 4 (0x80 to 0x9F)
+                printf("IO_ERROR_OUT: No device at port 4\n");
+        } else if (decoded <= 0x5F) {
+                // Port 5 (0xA0 to 0xBF)
+                printf("IO_ERROR_OUT: No device at port 5\n");
+        } else if (decoded <= 0x5F) {
+                // Port 6 (0xC0 to 0xDF)
+                printf("IO_ERROR_OUT: No device at port 6\n");
+        } else if (decoded <= 0x5F) {
+                // Port 7 (0xE0 to 0xFF)
+                printf("IO_ERROR_OUT: No device at port 7\n");
+        } else {
+                printf("IO_ERROR_OUT: Invalid port address: %#04x\n", port);
+        }
+}
+
+
+void machine_initialize(Machine *self) {
         self->cpu.context      = self;
         self->cpu.fetch_opcode =
         self->cpu.fetch        =
@@ -88,58 +147,114 @@ void machine_initialize(Machine *self)
         self->cpu.options      = Z80_MODEL_ZILOG_NMOS;
 
         /* Create and initialize devices... */
-        }
+}
 
 
-void machine_power(Machine *self, zbool state)
-        {
+void machine_power(Machine *self, zbool state) {
         if (state)
                 {
                 self->cycles = 0;
-                memset(self->memory, 0, 65536);
+                memset(self->memory, 0, MEMORY_SIZE);
                 }
 
         z80_power(&self->cpu, state);
-        }
+}
 
 
-void machine_reset(Machine *self)
-        {
+void machine_reset(Machine *self) {
         z80_instant_reset(&self->cpu);
+}
+
+void machine_run(Machine *self) {
+        z80_run(&self->cpu, Z80_MAXIMUM_CYCLES);
+}
+
+
+// void machine_run_frame(Machine *self)
+//         {
+//         /* CPU cycles before the INT signal */
+//         self->cycles += z80_execute(&self->cpu, CYCLES_AT_INT - self->cycles);
+
+//         /* CPU cycles during the INT signal */
+//         z80_int(&self->cpu, Z_TRUE);
+//         self->cycles += z80_run(&self->cpu, (CYCLES_AT_INT + CYCLES_PER_INT) - self->cycles);
+//         z80_int(&self->cpu, Z_FALSE);
+
+//         /* CPU cycles after the INT signal */
+//         self->cycles += z80_execute(&self->cpu, CYCLES_PER_FRAME - self->cycles);
+
+//         self->cycles -= CYCLES_PER_FRAME;
+//         }
+
+
+
+
+// TEST IMPLEM DEVICE
+
+zuint8 device_terminal_read(void *context) {
+        return 'H';
+        //return 0;
+}
+
+void device_terminal_write(void *context, zuint8 value) {
+        printf("%c", value);
+}
+
+zuint8 device_sound_read(void *context) {
+        return 0;
+}
+
+void device_sound_write(void *context, zuint8 value) {
+        printf("sound[%c]\n", value);
+}
+
+// TEST IMPLEM DEVICE
+
+int main(int argc, char *argv[]) {
+        // Parse arguments
+        if (argc < 2) {
+                printf("Usage: %s [romFile]\n", argv[0]);
+                exit(0);
         }
+        char* romFilePath = argv[1];
 
-
-void machine_run_frame(Machine *self)
-        {
-        /* CPU cycles before the INT signal */
-        self->cycles += z80_execute(&self->cpu, CYCLES_AT_INT - self->cycles);
-
-        /* CPU cycles during the INT signal */
-        z80_int(&self->cpu, Z_TRUE);
-        self->cycles += z80_run(&self->cpu, (CYCLES_AT_INT + CYCLES_PER_INT) - self->cycles);
-        z80_int(&self->cpu, Z_FALSE);
-
-        /* CPU cycles after the INT signal */
-        self->cycles += z80_execute(&self->cpu, CYCLES_PER_FRAME - self->cycles);
-
-        self->cycles -= CYCLES_PER_FRAME;
-        }
-
-int main() {
         // Setup virtual Pat80 computer
         Z80 pat80Cpu = {};
-        Device pat80Devices[] = {};
-        zuint8  pat80Memory[65536] = {0};
-
         Machine pat80 = {
-                /*zusize*/  .cycles = 0,
-                /*zuint8*/  .memory = *pat80Memory,
-                /*Z80*/     .cpu = pat80Cpu,
-                /*Device**/ .devices = pat80Devices,
-                /*zusize*/  .device_count = 255
+                /*zusize*/  .cycles = 100000,
+                /*Z80*/     .cpu = pat80Cpu
         };
-        
+
         machine_initialize(&pat80);
         machine_power(&pat80, Z_TRUE);
+
+        // Load ROM into memory
+        FILE *romFile;
+        romFile = fopen(romFilePath,"rb");
+        if (romFile == NULL) {
+                printf("Unable to open rom file at %s", romFilePath);
+                exit(1);
+        }
+        fread(&pat80.memory,ROM_SIZE,1,romFile); // load rom from file into memory, up >
+        fclose(romFile);
+
+	// Declare system devices
+	Device patoTerminal = {
+                .read = *device_terminal_read,
+                .write = *device_terminal_write,
+        };
+        Device patoSound = {
+                .read = *device_sound_read,
+                .write = *device_sound_write,
+        };
+
+	Device patoDevices[2] = {
+                patoTerminal,   // Port 0 (0x00 to 0x1F)
+                patoSound       // Port 1 (0x20 to 0x3F)
+        };
+	pat80.devices = patoDevices;
+        pat80.device_count = 2;
+
         machine_reset(&pat80);
-}
+        machine_run(&pat80);
+}