wip

src/lib.rs

@@ -0,0 +1,30 @@
+#![no_std]
+
+use rgb::Rgb;
+
+/// Scales the requested brightness to stay within power consumption limits
+pub fn brightness_for_mw(total_mw : u32, target : u8, max_power: u32) -> u8 {
+    let target32 = target as u32;
+    let requested_mw = (total_mw * target32) / 256;
+
+    if requested_mw > max_power {
+        ((target32 * max_power) / requested_mw) as u8
+    } else {
+        target
+    }
+}
+
+/// Calculate the estimated power draw of a single pixel, in milliwatts
+pub fn as_milliwatts(pixel: &Rgb<u8>) -> u32 {
+    // These values are copied from the original FastLED implementation
+    const RED_MW : u32   = 16 * 5; //< 16mA @ 5v = 80mW
+    const GREEN_MW : u32 = 11 * 5; //< 11mA @ 5v = 55mW
+    const BLUE_MW : u32  = 15 * 5; //< 15mA @ 5v = 75mW
+    const DARK_MW : u32  =      5; //<  1mA @ 5v =  5mW
+
+    let red = (pixel.r as u32 * RED_MW).wrapping_shr(8);
+    let green = (pixel.g as u32 * GREEN_MW).wrapping_shr(8);
+    let blue = (pixel.b as u32 * BLUE_MW).wrapping_shr(8);
+
+    red + green + blue + DARK_MW
+}