From e50fda62be3e79c60bd6510d53d869adb058aff5 Mon Sep 17 00:00:00 2001
From: Peter Evans <peter@modul8r.com>
Date: Sun, 25 Feb 2018 15:41:37 -0600
Subject: [PATCH] Add step command

---
 include/vm_debug.h   |  1 +
 src/apple2.c         |  4 ++++
 src/apple2.reflect.c | 12 ++++--------
 src/mos6502.c        |  2 ++
 src/vm_debug.c       | 11 +++++++++++
 tests/vm_debug.c     | 21 +++++++++++++++++++++
 6 files changed, 43 insertions(+), 8 deletions(-)

diff --git a/include/vm_debug.h b/include/vm_debug.h
index fe8212b..776c5a9 100644
--- a/include/vm_debug.h
+++ b/include/vm_debug.h
@@ -82,6 +82,7 @@ extern DEBUG_CMD(printaddr);
 extern DEBUG_CMD(printstate);
 extern DEBUG_CMD(quit);
 extern DEBUG_CMD(resume);
+extern DEBUG_CMD(step);
 extern DEBUG_CMD(unbreak);
 extern DEBUG_CMD(writeaddr);
 extern DEBUG_CMD(writestate);
diff --git a/src/apple2.c b/src/apple2.c
index b372862..fa7d738 100644
--- a/src/apple2.c
+++ b/src/apple2.c
@@ -351,6 +351,10 @@ apple2_run_loop(apple2 *mach)
     vm_reflect_pause(NULL);
 
     while (vm_screen_active(mach->screen)) {
+        if (vm_debug_broke(mach->cpu->PC)) {
+            mach->paused = true;
+        }
+
         // If we're paused, then just re-loop until we're not
         if (mach->paused) {
             char *input = vm_debug_prompt();
diff --git a/src/apple2.reflect.c b/src/apple2.reflect.c
index bdace0b..acbf3d0 100644
--- a/src/apple2.reflect.c
+++ b/src/apple2.reflect.c
@@ -33,8 +33,7 @@ REFLECT(apple2_reflect_cpu_info)
     mos6502 *cpu = (mos6502 *)vm_di_get(VM_CPU);
     FILE *out = (FILE *)vm_di_get(VM_OUTPUT);
 
-    fprintf(out, "REGISTERS:\n");
-    fprintf(out, "  A:%02x X:%02x Y:%02x P:%02x S:%02x PC:%04x\n",
+    fprintf(out, "CPU:  A:%02x X:%02x Y:%02x P:%02x S:%02x PC:%04x\n",
             cpu->A, cpu->X, cpu->Y, cpu->P, cpu->S, cpu->PC);
 }
 
@@ -48,12 +47,9 @@ REFLECT(apple2_reflect_machine_info)
     apple2 *mach = (apple2 *)vm_di_get(VM_MACHINE);
     FILE *out = (FILE *)vm_di_get(VM_OUTPUT);
 
-    fprintf(out, "MACHINE:\n");
-    fprintf(out, "  display_mode: %02x\n", mach->display_mode);
-    fprintf(out, "  color_mode: %02x\n", mach->color_mode);
-    fprintf(out, "  bank_switch: %02x\n", mach->bank_switch);
-    fprintf(out, "  memory_mode: %02x\n", mach->memory_mode);
-    fprintf(out, "  strobe: %02x\n", mach->strobe);
+    fprintf(out, "MACH: BS:%02x CM:%02x DM:%02x MM:%02x STROBE:%02x\n",
+            mach->bank_switch, mach->color_mode, mach->display_mode,
+            mach->memory_mode, mach->strobe);
 }
 
 /*
diff --git a/src/mos6502.c b/src/mos6502.c
index 1c0c9e7..2d95fac 100644
--- a/src/mos6502.c
+++ b/src/mos6502.c
@@ -364,6 +364,8 @@ mos6502_execute(mos6502 *cpu)
     mos6502_address_resolver resolver;
     mos6502_instruction_handler handler;
 
+    // We shouldn't normally get here, if there was a breakpoint, but we
+    // will in testing.
     if (vm_debug_broke(cpu->PC)) {
         return;
     }
diff --git a/src/vm_debug.c b/src/vm_debug.c
index bea7f46..339c9ed 100644
--- a/src/vm_debug.c
+++ b/src/vm_debug.c
@@ -41,6 +41,8 @@ vm_debug_cmd cmdtable[] = {
         "Quit the emulator", },
     { "resume", "r", vm_debug_cmd_resume, 0, "",
         "Resume execution", },
+    { "step", "s", vm_debug_cmd_step, 0, "",
+        "Execute the current opcode and break at the next", },
     { "unbreak", "u", vm_debug_cmd_unbreak, 1, "<addr>",
         "Remove breakpoint at <addr>", },
     { "writeaddr", "wa", vm_debug_cmd_writeaddr, 2, "<addr> <byte>",
@@ -311,3 +313,12 @@ DEBUG_CMD(unbreak)
 {
     vm_debug_unbreak(args->addr1);
 }
+
+DEBUG_CMD(step)
+{
+    mos6502 *cpu = (mos6502 *)vm_di_get(VM_CPU);
+
+    vm_debug_unbreak(cpu->PC);
+    mos6502_execute(cpu);
+    vm_debug_break(cpu->PC);
+}
diff --git a/tests/vm_debug.c b/tests/vm_debug.c
index 6d3ec00..8c25b61 100644
--- a/tests/vm_debug.c
+++ b/tests/vm_debug.c
@@ -212,4 +212,25 @@ Test(vm_debug, unbreak_all)
     cr_assert_eq(vm_debug_broke(55555), false);
 }
 
+Test(vm_debug, cmd_step)
+{
+    // Just setting us up with some NOPs for the testing
+    mos6502_set(mach->cpu, 0, 0xEA);
+    mos6502_set(mach->cpu, 1, 0xEA);
+    mos6502_set(mach->cpu, 2, 0xEA);
+    mos6502_set(mach->cpu, 3, 0xEA);
+
+    vm_debug_break(1);
+    mos6502_execute(mach->cpu);
+    cr_assert_eq(mach->cpu->PC, 1);
+
+    // We should go nowhere here
+    mos6502_execute(mach->cpu);
+    cr_assert_eq(mach->cpu->PC, 1);
+
+    // Step should a) unbreak at PC, b) execute at PC
+    vm_debug_cmd_step(&args);
+    cr_assert_eq(mach->cpu->PC, 2);
+}
+
 /* Test(vm_debug, quit) */