1 files changed, 51 insertions, 0 deletions
diff --git a/libraries/daguerre/source/psf.cpp b/libraries/daguerre/source/psf.cpp
new file mode 100644
index 0000000..81f722a
--- /dev/null
+++ b/libraries/daguerre/source/psf.cpp
@@ -0,0 +1,51 @@
+#include <daguerre/psf.hpp>
+
+namespace daguerre {
+
+  //TODO: this assumes the font is in psf2 format, and has a unicode table
+  std::optional<fixed_font<bool>> try_load_psf(FILE *input) {
+
+    uint32_t header[8];
+    if (fread(header, 4, 8, input) != 8)
+      return {};
+
+    const uint32_t glyphs_start = header[2];
+    const uint32_t glyph_count = header[4];
+    const uint32_t glyph_length = header[5];
+    const uint32_t height = header[6];
+    const uint32_t width = header[7];
+
+    fixed_font<bool> font(width, height);
+
+    const uint32_t unicode_start = glyphs_start + glyph_count * glyph_length;
+    fseek(input, unicode_start, SEEK_SET);
+
+    uint32_t indices[128];
+
+    for (uint32_t index = 0; index < glyph_count; ++index) {
+      uint8_t ch;
+      fread(&ch, 1, 1, input);
+      if (ch < 128)
+        indices[ch] = index;
+      do
+        if (fread(&ch, 1, 1, input) != 1)
+          return {};
+      while (ch != 0xff);
+    }
+
+    for (uint8_t ch = 0; ch < 128; ++ch) {
+      fseek(input, glyphs_start + glyph_length * indices[ch], SEEK_SET);
+      for (unsigned h = 0; h < height; ++h)
+        for (unsigned wb = 0; wb < width; wb += 8) {
+          uint8_t byte;
+          fread(&byte, 1, 1, input);
+          for (unsigned x = 0; x < 8 && wb + x < width; ++x)
+            font.glyphs[ch].at(wb + x, h) = (byte >> (7 - x)) & 1;
+        }
+    }
+
+    return font;
+
+  }
+
+}