Add prompt; quit command; breakpoints

include/vm_debug.h

@@ -1,6 +1,8 @@
 #ifndef _VM_DEBUG_H_
 #define _VM_DEBUG_H_
 
+#include <stdbool.h>
+
 struct vm_debug_args;
 typedef struct vm_debug_args vm_debug_args;
 
@@ -64,14 +66,20 @@ struct vm_debug_args {
 #define DEBUG_CMD(x) \
     void vm_debug_cmd_##x (vm_debug_args *args)
 
+extern bool vm_debug_broke(int);
+extern char *vm_debug_prompt();
 extern vm_debug_cmd *vm_debug_find_cmd(const char *);
+extern void vm_debug_break(int);
 extern void vm_debug_execute(const char *);
+extern void vm_debug_quit();
 
 extern DEBUG_CMD(help);
 extern DEBUG_CMD(jump);
 extern DEBUG_CMD(printaddr);
 extern DEBUG_CMD(printstate);
+extern DEBUG_CMD(quit);
 extern DEBUG_CMD(resume);
 extern DEBUG_CMD(writeaddr);
+extern DEBUG_CMD(writestate);
 
 #endif

src/apple2.c

@@ -15,7 +15,9 @@
 #include "mos6502.dis.h"
 #include "objstore.h"
 #include "option.h"
+#include "vm_debug.h"
 #include "vm_di.h"
+#include "vm_reflect.h"
 #include "vm_segment.h"
 
 /*
@@ -346,11 +348,18 @@ apple2_run_loop(apple2 *mach)
     }
 
     out = (FILE *)vm_di_get(VM_OUTPUT);
+    vm_reflect_pause(NULL);
 
     while (vm_screen_active(mach->screen)) {
         // If we're paused, then just re-loop until we're not
         if (mach->paused) {
-            usleep(100000);     // but rest our weary head for a bit
+            char *input = vm_debug_prompt();
+
+            if (input != NULL) {
+                vm_debug_execute(input);
+            }
+
+            free(input);
             continue;
         }
 

src/vm_debug.c

@@ -2,6 +2,7 @@
  * vm_debug.c
  */
 
+#include <ctype.h>
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -12,6 +13,18 @@
 #include "vm_di.h"
 #include "vm_reflect.h"
 
+/*
+ * The largest address size we can set a breakpoint for
+ */
+#define BREAKPOINTS_MAX 0x10000
+
+/*
+ * A table of breakpoints, arranged by address in a CPU. If
+ * breakpoints[i] is zero, then there is no breakpoint. If it is
+ * non-zero, then there is a breakpoint at address i.
+ */
+static int breakpoints[BREAKPOINTS_MAX];
+
 vm_debug_cmd cmdtable[] = {
     { "help", "h", vm_debug_cmd_help, 0, "",
         "Print out this list of commands", },
@@ -21,10 +34,14 @@ vm_debug_cmd cmdtable[] = {
         "Print the value at memory address <addr>", },
     { "printstate", "ps", vm_debug_cmd_printstate, 0, "",
         "Print the machine and CPU state", },
+    { "quit", "q", vm_debug_cmd_quit, 0, "",
+        "Quit the emulator", },
     { "resume", "r", vm_debug_cmd_resume, 0, "",
         "Resume execution", },
     { "writeaddr", "wa", vm_debug_cmd_writeaddr, 2, "<addr> <byte>",
         "Write <byte> at <addr>", },
+    { "writestate", "ws", vm_debug_cmd_writestate, 2, "<reg> <byte>",
+        "Write <byte> into <reg>", },
 };
 
 #define CMDTABLE_SIZE (sizeof(cmdtable) / sizeof(vm_debug_cmd))
@@ -34,7 +51,7 @@ vm_debug_next_arg(char **str)
 {
     char *tok;
 
-    while ((tok = strsep(str, " "))) {
+    while ((tok = strsep(str, " "))){
         if (tok == NULL) {
             return NULL;
         }
@@ -46,7 +63,8 @@ vm_debug_next_arg(char **str)
         break;
     }
 
-    return tok; }
+    return tok;
+}
 
 int
 vm_debug_addr(const char *str)
@@ -65,6 +83,48 @@ vm_debug_addr(const char *str)
     return addr;
 }
 
+void
+vm_debug_break(int addr)
+{
+    if (addr < 0 || addr >= BREAKPOINTS_MAX) {
+        return;
+    }
+
+    breakpoints[addr] = 1;
+}
+
+bool
+vm_debug_broke(int addr)
+{
+    if (addr < 0 || addr >= BREAKPOINTS_MAX) {
+        return false;
+    }
+
+    return breakpoints[addr] != 0;
+}
+
+char *
+vm_debug_prompt()
+{
+    char buf[256];
+    FILE *stream = (FILE *)vm_di_get(VM_OUTPUT);
+
+    if (feof(stdin)) {
+        return NULL;
+    }
+
+    fputs("erc> ", stream);
+
+    if (fgets(buf, 256, stdin) == NULL) {
+        return NULL;
+    }
+
+    // Cut off the newline character, if there is one
+    buf[strlen(buf)-1] = '\0';
+
+    return strdup(buf);
+}
+
 void
 vm_debug_execute(const char *str)
 {
@@ -126,6 +186,8 @@ vm_debug_execute(const char *str)
     }
 
     cmd->handler(&args);
+
+    free(ebuf);
 }
 
 static int
@@ -200,3 +262,21 @@ DEBUG_CMD(writeaddr)
     mos6502 *cpu = (mos6502 *)vm_di_get(VM_CPU);
     mos6502_set(cpu, args->addr1, args->addr2);
 }
+
+DEBUG_CMD(writestate)
+{
+    mos6502 *cpu = (mos6502 *)vm_di_get(VM_CPU);
+
+    switch (tolower(*args->target)) {
+        case 'a': cpu->A = args->addr1; break;
+        case 'p': cpu->P = args->addr1; break;
+        case 's': cpu->S = args->addr1; break;
+        case 'x': cpu->X = args->addr1; break;
+        case 'y': cpu->Y = args->addr1; break;
+    }
+}
+
+DEBUG_CMD(quit)
+{
+    exit(0);
+}

tests/vm_debug.c

@@ -124,3 +124,57 @@ Test(vm_debug, cmd_writeaddr)
     vm_debug_cmd_writeaddr(&args);
     cr_assert_eq(mos6502_get(mach->cpu, args.addr1), args.addr2);
 }
+
+Test(vm_debug, cmd_writestate)
+{
+    args.addr1 = 111;
+    args.target = "a";
+    vm_debug_cmd_writestate(&args);
+    cr_assert_eq(mach->cpu->A, args.addr1);
+
+    args.addr1 = 112;
+    args.target = "x";
+    vm_debug_cmd_writestate(&args);
+    cr_assert_eq(mach->cpu->X, args.addr1);
+
+    args.addr1 = 113;
+    args.target = "y";
+    vm_debug_cmd_writestate(&args);
+    cr_assert_eq(mach->cpu->Y, args.addr1);
+
+    args.addr1 = 114;
+    args.target = "p";
+    vm_debug_cmd_writestate(&args);
+    cr_assert_eq(mach->cpu->P, args.addr1);
+
+    args.addr1 = 115;
+    args.target = "s";
+    vm_debug_cmd_writestate(&args);
+    cr_assert_eq(mach->cpu->S, args.addr1);
+}
+
+Test(vm_debug, break)
+{
+    vm_debug_break(0x2);
+
+    mos6502_set(mach->cpu, 0, 0xEA);
+    mos6502_set(mach->cpu, 1, 0xEA);
+    mos6502_set(mach->cpu, 2, 0xEA);
+    mos6502_set(mach->cpu, 3, 0xEA);
+
+    mos6502_execute(mach->cpu);
+    cr_assert_eq(mach->cpu->PC, 1);
+    mos6502_execute(mach->cpu);
+    cr_assert_eq(mach->cpu->PC, 2);
+    mos6502_execute(mach->cpu);
+    cr_assert_eq(mach->cpu->PC, 2);
+}
+
+Test(vm_debug, broke)
+{
+    cr_assert_eq(vm_debug_broke(0x23), false);
+    vm_debug_break(0x23);
+    cr_assert_eq(vm_debug_broke(0x23), true);
+}
+
+/* Test(vm_debug, quit) */