From 5611462c089599e5318eb565c7fb38d45a1e19dc Mon Sep 17 00:00:00 2001
From: jmug <u.g.a.mariano@gmail.com>
Date: Sun, 18 May 2025 23:06:58 -0700
Subject: [PATCH] Add the assembly blink to the sdk examble.

Signed-off-by: jmug <u.g.a.mariano@gmail.com>
---
 CMakeLists.txt |  1 +
 hello_world.c  | 15 +++++++++------
 led.s          | 25 +++++++++++++++++++++++++
 3 files changed, 35 insertions(+), 6 deletions(-)
 create mode 100644 led.s

diff --git a/CMakeLists.txt b/CMakeLists.txt
index a006037..891544c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -13,6 +13,7 @@ pico_sdk_init()
 # rest of your project
 add_executable(hello_world
     hello_world.c
+    led.s
 )
 
 # Add pico_stdlib library which aggregates commonly used features
diff --git a/hello_world.c b/hello_world.c
index e588b0e..668c54f 100644
--- a/hello_world.c
+++ b/hello_world.c
@@ -41,13 +41,16 @@ void pico_set_led(bool led_on) {
 #endif
 }
 
+void blink();
+
 int main() {
     int rc = pico_led_init();
     hard_assert(rc == PICO_OK);
-    while (true) {
-        pico_set_led(true);
-        sleep_ms(LED_DELAY_MS);
-        pico_set_led(false);
-        sleep_ms(LED_DELAY_MS);
-    }
+    blink();
+    /* while (true) { */
+    /*     pico_set_led(true); */
+    /*     sleep_ms(LED_DELAY_MS); */
+    /*     pico_set_led(false); */
+    /*     sleep_ms(LED_DELAY_MS); */
+    /* } */
 }
diff --git a/led.s b/led.s
new file mode 100644
index 0000000..3135625
--- /dev/null
+++ b/led.s
@@ -0,0 +1,25 @@
+.section .text
+.equ sio_base, 		0xd0000000
+.equ big_num,		0x00f00000	// For the delay.
+
+.thumb_func
+.global blink
+blink:
+	ldr r0, =sio_base
+	mov r1, #1
+	lsl r1, r1, #25
+led_loop:
+	str r1, [r0, #0x18] // GPIO_OUT_SET
+	ldr r3, =big_num
+	bl delay
+
+	str r1, [r0, #0x20] // GPIO_OUT_CLR
+	ldr r3, =big_num
+	bl delay
+
+	b led_loop
+
+delay:
+	sub r3, #1
+	bne delay
+	bx lr