Add option to skip bios code so I can start checking out test roms

Former-commit-id: b78c8d9807ba3097d641a57ec7fcd500b32b4d96

src/bin/cli.yml

@@ -15,4 +15,7 @@ subcommands:
                 long: game-rom
                 takes_value: true
                 help: Sets the game-rom file to use
-                required: true
+                required: true
+            - skip_bios:
+                long: skip-bios
+                help: Skip running bios and start from the ROM instead.

src/bin/main.rs

@@ -12,6 +12,11 @@ use rustboyadvance_ng::util::read_bin_file;
 use rustboyadvance_ng::{GBAResult, GameBoyAdvance};
 
 fn run_debug(matches: &ArgMatches) -> GBAResult<()> {
+    let skip_bios = match matches.occurrences_of("skip_bios") {
+        0 => false,
+        _ => true
+    };
+
     let bios_bin = read_bin_file(matches.value_of("bios").unwrap_or_default())?;
     let rom_bin = read_bin_file(matches.value_of("game_rom").unwrap())?;
 
@@ -21,6 +26,19 @@ fn run_debug(matches: &ArgMatches) -> GBAResult<()> {
     let mut core = Core::new();
     core.reset();
     core.set_verbose(true);
+    if skip_bios {
+        core.gpr[13] = 0x0300_7f00;
+        core.gpr_banked_r13[0] = 0x0300_7f00; // USR/SYS
+        core.gpr_banked_r13[0] = 0x0300_7f00; // FIQ
+        core.gpr_banked_r13[0] = 0x0300_7fa0; // IRQ
+        core.gpr_banked_r13[0] = 0x0300_7fe0; // SVC
+        core.gpr_banked_r13[0] = 0x0300_7f00; // ABT
+        core.gpr_banked_r13[0] = 0x0300_7f00; // UND
+
+        core.pc = 0x0800_0000;
+
+        core.cpsr.set(0x5f);
+    }
 
     let gba = GameBoyAdvance::new(core, bios_bin, gamepak);