penguin86/pato-z80-home-computer
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Emulator: working decoding logic, outputting terminal to stdout

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This commit is contained in:
Daniele Verducci 2025-02-07 08:18:14 +01:00
parent 882f258ad8
commit b667561da9
2 changed files with 137 additions and 31 deletions
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7
pat80-computer/software/z80-assembly/os/tests/out_single_char.asm Normal file
View File

@ -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

159
pat80-emulator/main.c
View File

@ -14,7 +14,6 @@ typedef struct {
void* context;
zuint8 (* read)(void *context);
void (* write)(void *context, zuint8 value);
zuint16 assigned_port;
} Device;
typedef struct {
@ -26,17 +25,6 @@ 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) {
return address < MEMORY_SIZE ? self->memory[address] : 0xFF;
}
@ -49,16 +37,91 @@ static void machine_cpu_write(Machine *self, zuint16 address, zuint8 value) {
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;
// 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;
}
if (decoded <= 0x3F) {
// Port 1 (0x20 to 0x3F): sound card (sn76489)
printf("\nsound_cmd[IN]: Not supported!\n");
return 0x00;
}
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);
}
}
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);
// 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);
}
}
@ -91,7 +154,7 @@ 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);
@ -123,6 +186,30 @@ void machine_run(Machine *self) {
// 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) {
@ -133,8 +220,13 @@ int main(int argc, char *argv[]) {
// Setup virtual Pat80 computer
Z80 pat80Cpu = {};
Device pat80Devices[] = {};
zuint8 pat80Memory[65536] = {0};
Machine pat80 = {
/*zusize*/ .cycles = 100000,
/*Z80*/ .cpu = pat80Cpu
};
machine_initialize(&pat80);
machine_power(&pat80, Z_TRUE);
// Load ROM into memory
FILE *romFile;
@ -143,19 +235,26 @@ int main(int argc, char *argv[]) {
printf("Unable to open rom file at %s", romFilePath);
exit(1);
}
fread(pat80Memory,ROM_SIZE,1,romFile); // load rom from file into memory, up to ROM_SIZE
fread(&pat80.memory,ROM_SIZE,1,romFile); // load rom from file into memory, up >
fclose(romFile);
Machine pat80 = {
/*zusize*/ .cycles = 0,
/*zuint8*/ .memory = *pat80Memory,
/*Z80*/ .cpu = pat80Cpu,
/*Device**/ .devices = pat80Devices,
/*zusize*/ .device_count = 255
// Declare system devices
Device patoTerminal = {
.read = *device_terminal_read,
.write = *device_terminal_write,
};
Device patoSound = {
.read = *device_sound_read,
.write = *device_sound_write,
};
machine_initialize(&pat80);
machine_power(&pat80, Z_TRUE);
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);
}