Replace blink example with morse example

src/main.zig

@@ -2,13 +2,7 @@ const sdk = @import("sdk.zig");
 
 const std = @import("std");
 
-const LED_DELAY_MS = blk: {
-    if (@hasDecl(sdk, "LED_DELAY_MS")) {
-        break :blk sdk.LED_DELAY_MS;
-    } else {
-        break :blk 250;
-    }
-};
+const morse = @import("morse.zig");
 
 /// Perform initialisation
 fn picoLedInit() c_int {
@@ -39,9 +33,7 @@ export fn main() callconv(.C) c_int {
     const rc = picoLedInit();
     sdk.hardAssert(rc == sdk.PICO_OK);
     while (true) {
-        picoSetLed(true);
-        sdk.sleep_ms(LED_DELAY_MS);
-        picoSetLed(false);
-        sdk.sleep_ms(LED_DELAY_MS);
+        morse.putMorseString("Hello World");
+        sdk.sleep_ms(1000);
     }
 }

src/morse.zig

@@ -0,0 +1,86 @@
+const sdk = @import("sdk.zig");
+
+const std = @import("std");
+
+const DOT_PERIOD_MS = 100;
+
+const morse_letters = &[_][:0]const u8{
+    ".-", // A
+    "-...", // B
+    "-.-.", // C
+    "-..", // D
+    ".", // E
+    "..-.", // F
+    "--.", // G
+    "....", // H
+    "..", // I
+    ".---", // J
+    "-.-", // K
+    ".-..", // L
+    "--", // M
+    "-.", // N
+    "---", // O
+    ".--.", // P
+    "--.-", // Q
+    ".-.", // R
+    "...", // S
+    "-", // T
+    "..-", // U
+    "...-", // V
+    ".--", // W
+    "-..-", // X
+    "-.--", // Y
+    "--..", // Z
+};
+
+/// Perform initialisation
+fn picoLedInit() c_int {
+    if (@hasDecl(sdk, "PICO_DEFAULT_LED_PIN")) {
+        // A device like Pico that uses a GPIO for the LED will define PICO_DEFAULT_LED_PIN
+        // so we can use normal GPIO functionality to turn the led on and off
+        sdk.gpio_init(sdk.PICO_DEFAULT_LED_PIN);
+        sdk.gpio_set_dir(sdk.PICO_DEFAULT_LED_PIN, sdk.GPIO_OUT != 0); // Cast to bool by: <int> != 0
+        return sdk.PICO_OK;
+    } else if (@hasDecl(sdk, "CYW43_WL_GPIO_LED_PIN")) {
+        // For Pico W devices we need to initialise the driver etc
+        return sdk.cyw43_arch_init();
+    }
+}
+
+/// Turn the led on or off
+fn picoSetLed(led_on: bool) void {
+    if (@hasDecl(sdk, "PICO_DEFAULT_LED_PIN")) {
+        // Just set the GPIO on or off
+        sdk.gpio_put(sdk.PICO_DEFAULT_LED_PIN, led_on);
+    } else if (@hasDecl(sdk, "CYW43_WL_GPIO_LED_PIN")) {
+        // Ask the wifi "driver" to set the GPIO on or off
+        sdk.cyw43_arch_gpio_put(sdk.CYW43_WL_GPIO_LED_PIN, led_on);
+    }
+}
+
+inline fn putMorseLetter(pattern: [:0]const u8) void {
+    for (pattern) |value| {
+        picoSetLed(true);
+        if (value == '.') {
+            sdk.sleep_ms(DOT_PERIOD_MS);
+        } else {
+            sdk.sleep_ms(DOT_PERIOD_MS * 3);
+        }
+        picoSetLed(false);
+        sdk.sleep_ms(DOT_PERIOD_MS);
+    }
+    sdk.sleep_ms(DOT_PERIOD_MS * 2);
+}
+
+pub inline fn putMorseString(comptime str: [:0]const u8) void {
+    for (str) |value| {
+        if (value >= 'A' and value <= 'Z') {
+            putMorseLetter(morse_letters[value - 'A']);
+        } else if (value >= 'a' and value <= 'z') {
+            putMorseLetter(morse_letters[value - 'a']);
+        } else if (value == ' ') {
+            sdk.sleep_ms(DOT_PERIOD_MS * 4);
+        }
+    }
+    _ = sdk.printf(str ++ "\n");
+}