main: add USB rescue support for chainloader

Author: pcm720

Makefile

@@ -13,7 +13,7 @@ export HEADER
 # ---{BUILD CFG}--- #
 HAS_EMBED_IRX ?= 1# whether to embed or not non vital IRX (wich will be loaded from memcard files)
 DEBUG ?= 0
-CHAINLOAD ?= 0 # Only inits the system and boots CHAINLOAD_PATH from the memory card
+CHAINLOAD ?= 0 # Only inits the system and boots CHAINLOAD_PATH from the memory card. If specified file doesn't exist, attempts to boot RESCUE.ELF from USB
 CHAINLOAD_PATH ?= "mc?:BOOT/PAYLOAD.ELF"
 PSX ?= 0 # PSX DESR support
 HDD ?= 0 #wether to add internal HDD support

src/main.c

@@ -191,7 +191,15 @@ int main(int argc, char *argv[])
     init_scr();
     scr_setCursor(0); // get rid of annoying that cursor.
     scr_printf("\n\n\n"CHAINLOAD_PATH" not found\n");
-    while (1) {}
+    sleep(2);
+    j = LoadUSBIRX();
+    if (j != 0) {
+        scr_setfontcolor(0x0000ff);
+        scr_printf("ERROR: could not load USB modules (%d)\n", j);
+        scr_setfontcolor(0xffffff);
+        __builtin_trap();
+    }
+    EMERGENCY();
 #endif
 
     DPRINTF("Init pads\n");