Add start of emulator, debugger
diff --git a/dbg.c b/dbg.c
new file mode 100644
index 0000000..bdc2b31
--- /dev/null
+++ b/dbg.c
@@ -0,0 +1,52 @@
+#include "dbg.h"
+#include "cpu.h"
+
+#include <readline/readline.h>
+#include <readline/history.h>
+#include <string.h>
+#include <stdlib.h>
+
+void debug(cpu_t *cpu)
+{
+ while (true)
+ {
+ char *input = readline("\033[33m> \033[0m");
+ if (!input)
+ continue;
+
+ char *tok = strtok(input, " \t\r\n\v");
+
+ if (!strcmp(tok, "step") || !strcmp(tok, "s"))
+ {
+ step(cpu);
+ }
+ else if (!strcmp(tok, "show") || !strcmp(tok, "print"))
+ {
+ if ((tok = strtok(NULL, " ")))
+ {
+ char *ok = 0;
+ if (tok[0] == '$')
+ {
+ uint16_t addr = strtol(tok + 1, &ok, 16);
+
+ if (ok == 0)
+ {
+ printf("Memory:\n");
+ printf("\t$%x %x\n", addr, cpu->mem[addr]);
+ printf("\t$%x %x\n", addr + 1, cpu->mem[addr + 1]);
+ }
+ }
+ else
+ {
+ printf("Registers:\n");
+
+ #define R(r) printf("\t" #r ": %x\n", cpu->regs[r]);
+ REGISTERS
+ #undef R
+ }
+ }
+ }
+
+ add_history(input);
+ }
+}