2 files changed, 72 insertions, 0 deletions
diff --git a/src/components/rle/RleDecoder.cpp b/src/components/rle/RleDecoder.cpp
new file mode 100644
index 00000000..19a90fda
--- /dev/null
+++ b/src/components/rle/RleDecoder.cpp
@@ -0,0 +1,39 @@
+#include "RleDecoder.h"
+
+using namespace Pinetime::Tools;
+
+RleDecoder::RleDecoder(const uint8_t *buffer, size_t size) : buffer{buffer}, size{size} {
+
+}
+
+RleDecoder::RleDecoder(const uint8_t *buffer, size_t size, uint16_t foregroundColor, uint16_t backgroundColor) : RleDecoder{buffer, size} {
+  this->foregroundColor = foregroundColor;
+  this->backgroundColor = backgroundColor;
+}
+
+
+void RleDecoder::DecodeNext(uint8_t *output, size_t maxBytes) {
+  for (;encodedBufferIndex<size; encodedBufferIndex++) {
+    uint8_t rl = buffer[encodedBufferIndex] - processedCount;
+    while (rl) {
+      output[bp] = color >> 8;
+      output[bp + 1] = color & 0xff;
+      bp += 2;
+      rl -= 1;
+      processedCount++;
+
+      if (bp >= maxBytes) {
+        bp = 0;
+        y += 1;
+        return;
+      }
+    }
+    processedCount = 0;
+
+    if (color == backgroundColor)
+      color = foregroundColor;
+    else
+      color = backgroundColor;
+  }
+}
+
diff --git a/src/components/rle/RleDecoder.h b/src/components/rle/RleDecoder.h
new file mode 100644
index 00000000..0f607fb8
--- /dev/null
+++ b/src/components/rle/RleDecoder.h
@@ -0,0 +1,33 @@
+#pragma once
+
+#include <cstdint>
+#include <cstddef>
+
+namespace Pinetime {
+  namespace Tools {
+    /* 1-bit RLE decoder. Provide the encoded buffer to the constructor and then call DecodeNext() by
+     * specifying the output (decoded) buffer and the maximum number of bytes this buffer can handle.
+     *
+     * Code from https://github.com/daniel-thompson/wasp-bootloader by Daniel Thompson released under the MIT license.
+     */
+    class RleDecoder {
+    public:
+      RleDecoder(const uint8_t* buffer, size_t size);
+      RleDecoder(const uint8_t* buffer, size_t size, uint16_t foregroundColor, uint16_t backgroundColor);
+
+      void DecodeNext(uint8_t* output, size_t maxBytes);
+
+    private:
+      const uint8_t* buffer;
+      size_t size;
+
+      int encodedBufferIndex = 0;
+      int y = 0;
+      uint16_t bp = 0;
+      uint16_t foregroundColor = 0xffff;
+      uint16_t backgroundColor = 0;
+      uint16_t color = backgroundColor;
+      int processedCount = 0;
+    };
+  }
+}