Improve TBYB sequence

Add self check (1 == 1), which is only performed on first boot

Author: will-v-pi

Diff for: encrypted/hello_encrypted/hello_encrypted.c

@@ -15,10 +15,29 @@ int main() {
     stdio_init_all();
 
 #if PICO_CRT0_IMAGE_TYPE_TBYB
-    // If TBYB image, then buy it
-    uint8_t* buffer = malloc(4096);
-    rom_explicit_buy(buffer, 4096);
-    free(buffer);
+    boot_info_t boot_info = {};
+    int ret = rom_get_boot_info(&boot_info);
+    if (ret) {
+        // BOOT_TBYB_AND_UPDATE_FLAG_BUY_PENDING will always be set, but check anyway
+        if (boot_info.tbyb_and_update_info & BOOT_TBYB_AND_UPDATE_FLAG_BUY_PENDING) {
+            // Need to check flash_update_base is set to see if this is a TBYB update
+            uint32_t flash_update_base = boot_info.reboot_params[0];
+            if (flash_update_base) {
+                printf("Perform self-check... ");
+                if (1 == 1) {
+                    printf("passed\n");
+                } else {
+                    printf("failed - looping forever\n");
+                    while (true) sleep_ms(1000);
+                }
+            }
+            uint32_t buf_size = flash_update_base ? 4096 : 0;
+            uint8_t* buffer = flash_update_base ? malloc(buf_size) : NULL;
+            int ret = rom_explicit_buy(buffer, buf_size);
+            assert(ret == 0);
+            if (buffer) free(buffer);
+        }
+    }
 #endif
     extern char secret_data[];