diff --git a/.gitignore b/.gitignore
index e2b79f2..5a234ce 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,3 +6,4 @@
*.asm
*.map
*.lib
+.vscode
diff --git a/README.md b/README.md
index 8a841d6..e3f1e50 100644
--- a/README.md
+++ b/README.md
@@ -34,7 +34,20 @@ Handheld PC based on the original 6502 CPU that fits into a pocket.
# Simulator
-Pocket265 simulator is there to make FW developement easier, but it can be also used to get a feel for the computer usage. I2C memory and UART are not simulated. It uses [simak65](https://github.com/agkaminski/simak65) simulator code.
+Pocket265 simulator is there to make FW developement easier, but it can be also used to get a feel for the computer usage. Only UART is not simulated. It uses [simak65](https://github.com/agkaminski/simak65) simulator code.
+
+## Usage
+
+./pocket265-sim [OPTIONS]
+
+where options are:
+- -c: path to the computer ROM (obligatory),
+- -f: simulated CPU frequency, from 0 (max speed, no throttling) to 20000000 (Hz),
+- -r: simulated RAM size in bytes,
+- -e: simulated EEPROM file (will be updated after end of the simulation, if write is performed!),
+- -h: usage.
+
+## Builing
To run the simulation first build and install [simak65](https://github.com/agkaminski/simak65):
@@ -51,6 +64,8 @@ then build the simulator:
$ (cd sim && make all)
+## Running the simulation
+
In the `sim/` directory is a script that starts the simulator with memory initialized with Pocket265 firmware - `runsim.sh`. To run the simulator:
$ cd sim
diff --git a/sim/Makefile b/sim/Makefile
index 8615f22..7628c57 100644
--- a/sim/Makefile
+++ b/sim/Makefile
@@ -3,7 +3,7 @@ CFLAGS := -g -Wall -Werror -Wextra -Wno-type-limits -O2 -ansi -std=gnu99
DEBUG := -DNDEBUG
OUT = pocket265-sim
-OBJ = pocket265.o
+OBJ = pocket265.o i2c.o
LIB = simak65
%.o: %.c
diff --git a/sim/i2c.c b/sim/i2c.c
new file mode 100644
index 0000000..ccf5149
--- /dev/null
+++ b/sim/i2c.c
@@ -0,0 +1,146 @@
+/* 24xx I2C memory simulator
+ * Copyright A.K. 2018, 2023
+ */
+
+#include
+#include
+#include "i2c.h"
+
+void i2c_step(struct i2c_ctx *ctx, const struct i2c_bus *in, struct i2c_bus *out)
+{
+ *out = ctx->prevout;
+
+ if (in->scl) {
+ if (ctx->previn.sda && !in->sda) {
+ /* Start condition */
+ ctx->state = i2c_dev_addr;
+ ctx->regbit = 0;
+ }
+ else if (!ctx->previn.sda && in->sda) {
+ /* Stop condtion */
+ ctx->state = i2c_idle;
+ }
+ }
+
+ if (in->scl && !ctx->previn.scl) {
+ /* Rising edge */
+ switch (ctx->state) {
+ case i2c_dev_addr:
+ ctx->reg = (ctx->reg << 1) | !!in->sda;
+ if (++ctx->regbit > 7) {
+ ctx->regbit = 0;
+ if (ctx->devaddr == (ctx->reg >> 1)) {
+ if (ctx->reg & 1)
+ ctx->next = i2c_read;
+ else
+ ctx->next = i2c_addr;
+ ctx->state = i2c_ack;
+ }
+ else {
+ ctx->state = i2c_idle;
+ }
+ }
+ break;
+
+ case i2c_addr:
+ ctx->address = (ctx->address << 1) | !!in->sda;
+ ++ctx->regbit;
+ if (ctx->regbit == 8) {
+ ctx->state = i2c_ack;
+ ctx->next = i2c_addr;
+ }
+ else if (ctx->regbit > 15) {
+ ctx->regbit = 0;
+ ctx->next = i2c_write;
+ ctx->state = i2c_ack;
+ }
+ break;
+
+ case i2c_write:
+ ctx->reg = (ctx->reg << 1) | !!in->sda;
+ if (++ctx->regbit > 7) {
+ ctx->regbit = 0;
+ ctx->mem[ctx->address % ctx->memsz] = ctx->reg;
+ ++ctx->address;
+ ctx->next = i2c_write;
+ ctx->state = i2c_ack;
+ }
+ break;
+
+ case i2c_read:
+ ++ctx->regbit;
+ if (ctx->regbit == 9) {
+ if (in->sda) {
+ ctx->state = i2c_idle;
+ ctx->regbit = 0;
+ }
+ else {
+ ctx->regbit = 0;
+ ++ctx->address;
+ }
+ }
+ break;
+
+ case i2c_ack:
+ ctx->state = ctx->next;
+ break;
+
+ default:
+ break;
+ }
+ }
+ else if (!in->scl && ctx->previn.scl) {
+ /* Falling ege */
+ switch (ctx->state) {
+ case i2c_ack:
+ out->sda = 0;
+ break;
+
+ case i2c_read:
+ if (ctx->regbit == 0)
+ ctx->reg = ctx->mem[ctx->address % ctx->memsz];
+
+ if (ctx->regbit <= 7) {
+ out->sda = !!(ctx->reg & 0x80);
+ ctx->reg <<= 1;
+ }
+ else {
+ out->sda = 1;
+ }
+ break;
+
+ default:
+ out->sda = 1;
+ break;
+ }
+ }
+
+ ctx->previn = *in;
+ ctx->prevout = *out;
+}
+
+void i2c_destroy(struct i2c_ctx *ctx)
+{
+ free(ctx->mem);
+ ctx->mem = NULL;
+}
+
+int i2c_init(struct i2c_ctx *ctx, size_t memsz, uint8_t devaddr)
+{
+ ctx->previn = (struct i2c_bus){ .sda = 1, .scl = 1 };
+ ctx->prevout = (struct i2c_bus){ .sda = 1, .scl = 1 };
+
+ ctx->state = i2c_idle;
+ ctx->address = 0;
+ ctx->reg = 0;
+ ctx->regbit = 0;
+ ctx->devaddr = devaddr;
+
+ ctx->mem = malloc(memsz);
+ if (ctx->mem == NULL) {
+ return -1;
+ }
+ ctx->memsz = memsz;
+
+ return 0;
+}
diff --git a/sim/i2c.h b/sim/i2c.h
new file mode 100644
index 0000000..51a182f
--- /dev/null
+++ b/sim/i2c.h
@@ -0,0 +1,49 @@
+/* 24xx I2C memory simulator
+ * Copyright A.K. 2018, 2023
+ */
+
+#ifndef I2C_H_
+#define I2C_H_
+
+#include
+#include
+
+struct i2c_bus {
+ int sda;
+ int scl;
+};
+
+enum i2c_state {
+ i2c_idle,
+ i2c_dev_addr,
+ i2c_addr,
+ i2c_read,
+ i2c_write,
+ i2c_ack
+};
+
+struct i2c_ctx {
+ struct i2c_bus previn;
+ struct i2c_bus prevout;
+
+ uint8_t *mem;
+ size_t memsz;
+
+ uint16_t address;
+
+ uint8_t devaddr;
+
+ uint8_t reg;
+ uint8_t regbit;
+
+ enum i2c_state state;
+ enum i2c_state next;
+};
+
+void i2c_step(struct i2c_ctx *ctx, const struct i2c_bus *in, struct i2c_bus *out);
+
+void i2c_destroy(struct i2c_ctx *ctx);
+
+int i2c_init(struct i2c_ctx *ctx, size_t memsz, uint8_t devaddr);
+
+#endif
diff --git a/sim/pocket265.c b/sim/pocket265.c
index ac41c6d..3dc0479 100644
--- a/sim/pocket265.c
+++ b/sim/pocket265.c
@@ -17,6 +17,8 @@
#include
#include
+#include "i2c.h"
+
#define RAM_START 0x0000u
#define RAM_SIZE 0x2000u
@@ -32,16 +34,22 @@
#define NMI_ACK_ADDR 0xc800u
#define GPIO_ADDR 0xcc00u
+#define EEPROM_SIZE (32 * 1024)
+
+/* Memory */
static uint8_t *g_ram;
static size_t g_ramsz = RAM_SIZE;
static uint8_t g_rom[ROM_SIZE];
-static uint8_t g_gpio_out;
+/* I/O */
static char g_screen[12];
static int g_screen_update = 1;
static uint8_t g_key_row[6];
static int g_nmi = 1;
static volatile int g_exit = 0;
+static struct i2c_bus i2c_in;
+static struct i2c_bus i2c_out;
+static int g_romwp = 1;
static void pocket265_nmi_ack(void)
{
@@ -62,6 +70,8 @@ static uint8_t pocket265_keyread(uint16_t addr)
static uint8_t pocket265_ioread(uint16_t addr)
{
+ uint8_t gpio = 0;
+
switch (addr & PERIPH_ADDR_MASK) {
case KEYBOARD_ADDR:
return pocket265_keyread(addr);
@@ -69,7 +79,10 @@ static uint8_t pocket265_ioread(uint16_t addr)
pocket265_nmi_ack();
break;
case GPIO_ADDR:
- return g_gpio_out & 0xf;
+ gpio |= !!(i2c_out.sda && i2c_in.sda) << 1; /* SDA */
+ gpio |= !!(i2c_out.scl && i2c_in.scl) << 2; /* SCL */
+ gpio |= !!g_romwp << 3; /* ROM_WP */
+ return gpio |= 0xf1; /* Unused */
}
return 0xff;
@@ -88,16 +101,13 @@ static void pocket265_iowrite(uint16_t addr, uint8_t byte)
pocket265_nmi_ack();
break;
case GPIO_ADDR:
- g_gpio_out = byte & 0xf;
+ i2c_in.sda = !!(byte & (1 << 1));
+ i2c_in.scl = !!(byte & (1 << 2));
+ g_romwp = !!(byte & (1 << 3));
break;
}
}
-static int pocket265_is_rom_wp(void)
-{
- return (g_gpio_out & (1 << 3)) ? 1 : 0;
-}
-
static uint8_t pocket265_read(uint16_t addr)
{
if (addr >= RAM_START && addr < (RAM_START + g_ramsz))
@@ -114,7 +124,7 @@ static void pocket265_write(uint16_t addr, uint8_t byte)
{
if (addr >= RAM_START && addr < (RAM_START + g_ramsz))
g_ram[addr - RAM_START] = byte;
- else if (addr >= ROM_START && addr < (ROM_START + ROM_SIZE) && !pocket265_is_rom_wp())
+ else if (addr >= ROM_START && addr < (ROM_START + ROM_SIZE) && !g_romwp)
g_rom[addr - ROM_START] = byte;
else if (addr >= PERIPH_ADDR_START && addr <= PERIPH_ADDR_END)
pocket265_iowrite(addr, byte);
@@ -188,20 +198,20 @@ static useconds_t gettime_us(void)
static void usage(const char *p)
{
- printf("usage: %s -c [-r ] [-f ]\n", p);
+ printf("usage: %s -c [-r ] [ -e ] [-f ]\n", p);
}
static void sighandler(int n)
{
- (void)n;
+ (void)n;
- g_exit = 1;
+ g_exit = 1;
}
int main(int argc, char *argv[])
{
int c;
- FILE *firmware = NULL;
+ FILE *firmware = NULL, *eeprom = NULL;
struct simak65_cpustate cpu;
const struct simak65_bus ops = { .read = pocket265_read, .write = pocket265_write };
unsigned int cycles = 0;
@@ -209,8 +219,9 @@ int main(int argc, char *argv[])
useconds_t prev, now, prev_nmi = 0, prev_ui = 0, ns_per_cycle = 0;
int ns_error = 0;
static struct termios oldt, newt;
+ struct i2c_ctx i2c;
- while ((c = getopt(argc, argv, "c:f:r:h")) != -1) {
+ while ((c = getopt(argc, argv, "c:f:r:e:h")) != -1) {
switch (c) {
case 'c':
if ((firmware = fopen(optarg, "r")) == NULL) {
@@ -233,6 +244,12 @@ int main(int argc, char *argv[])
return 1;
}
break;
+ case 'e':
+ if ((eeprom = fopen(optarg, "r+")) == NULL) {
+ fprintf(stderr, "can't open EEPROM file %s\n", optarg);
+ return 1;
+ }
+ break;
case 'h':
usage(argv[0]);
return 0;
@@ -263,6 +280,14 @@ int main(int argc, char *argv[])
return 1;
}
+ if (i2c_init(&i2c, EEPROM_SIZE, 0x50) < 0) {
+ fprintf(stderr, "i2c init failed");
+ return 1;
+ }
+
+ if (eeprom != NULL)
+ (void)!fread(i2c.mem, 1, i2c.memsz, eeprom);
+
signal(SIGINT, sighandler);
tcgetattr(STDIN_FILENO, &oldt);
@@ -280,6 +305,7 @@ int main(int argc, char *argv[])
while (!g_exit) {
simak65_step(&cpu, &cycles);
+ i2c_step(&i2c, &i2c_in, &i2c_out);
now = gettime_us();
@@ -319,6 +345,14 @@ int main(int argc, char *argv[])
tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
+ if (eeprom != NULL) {
+ rewind(eeprom);
+ (void)!fwrite(i2c.mem, 1, i2c.memsz, eeprom);
+ fflush(eeprom);
+ fclose(eeprom);
+ }
+
+ i2c_destroy(&i2c);
free(g_ram);
return 0;