[Teton] Load a font file and write a character to the screen.

sys/teton/framebuffer/framebuffer.cpp

@@ -1,6 +1,7 @@
 #include "framebuffer/framebuffer.h"
 
-Framebuffer::Framebuffer(const FramebufferInfo& info) : fb_info_(info) {
+Framebuffer::Framebuffer(const FramebufferInfo& info)
+    : fb_info_(info), cursor_pos_(0) {
   uint64_t buff_size_bytes = fb_info_.height() * fb_info_.pitch();
   fb_memory_ = OwnedMemoryRegion::DirectPhysical(fb_info_.address_phys(),
                                                  buff_size_bytes);
@@ -11,3 +12,18 @@ void Framebuffer::DrawPixel(uint32_t row, uint32_t col, uint32_t pixel) {
   // Div by 4 because pitch is in bytes and fb_ is a 32bit array.
   fb_[(row * fb_info_.pitch() / 4) + col] = pixel;
 }
+
+void Framebuffer::DrawGlyph(uint8_t* glyph) {
+  uint32_t gl_width = 8;
+  uint32_t gl_height = 16;
+
+  for (uint8_t r = 0; r < gl_height; r++) {
+    for (uint8_t c = 0; c < gl_width; c++) {
+      if (((glyph[r] >> c) % 2) == 1) {
+        DrawPixel(r, gl_width - c - 1, 0xFFFF'FFFF);
+      } else {
+        DrawPixel(r, gl_width - c - 1, 0);
+      }
+    }
+  }
+};

sys/teton/framebuffer/framebuffer.h

@@ -9,6 +9,8 @@ class Framebuffer {
 
   void DrawPixel(uint32_t row, uint32_t col, uint32_t pixel);
 
+  void DrawGlyph(uint8_t* glyph);
+
  private:
   // FIXME: Implement Yunq copy or move so we
   // don't have to store a reference here.
@@ -16,4 +18,5 @@ class Framebuffer {
 
   OwnedMemoryRegion fb_memory_;
   uint32_t* fb_;
+  uint32_t cursor_pos_;
 };

sys/teton/framebuffer/psf.cpp

@@ -0,0 +1,46 @@
+#include "framebuffer/psf.h"
+
+#include <glacier/memory/move.h>
+#include <mammoth/debug.h>
+
+namespace {
+
+const uint32_t kMagic = 0x864AB572;
+
+}
+
+Psf::Psf(OwnedMemoryRegion&& psf_file)
+    : psf_file_(glcr::Move(psf_file)),
+      header_(reinterpret_cast<PsfHeader*>(psf_file_.vaddr())) {
+  EnsureValid();
+}
+
+void Psf::DumpHeader() {
+  dbgln("Magic: {x}", header_->magic);
+  dbgln("Version: {x}", header_->version);
+  dbgln("Header Sz: {x}", header_->headersize);
+  dbgln("Flags: {x}", header_->flags);
+  dbgln("Length: {x}", header_->numglyph);
+  dbgln("Glyph Size: {x}", header_->bytesperglyph);
+  dbgln("Height: {x}", header_->height);
+  dbgln("Width: {x}", header_->width);
+}
+
+void Psf::EnsureValid() {
+  if (header_->magic != kMagic) {
+    dbgln("PSF: Magic value: {x}", header_->magic);
+    crash("PSF: Invalid magic value", glcr::INVALID_ARGUMENT);
+  }
+
+  if (header_->version != 0) {
+    crash("PSF non-zero version", glcr::INVALID_ARGUMENT);
+  }
+
+  if (header_->height != 0x10) {
+    crash("PSF height other than 16 not handled", glcr::UNIMPLEMENTED);
+  }
+
+  if (header_->width != 0x8) {
+    crash("PSF width other than 8 not handled", glcr::UNIMPLEMENTED);
+  }
+}

sys/teton/framebuffer/psf.h

@@ -0,0 +1,34 @@
+#pragma once
+
+#include <mammoth/memory_region.h>
+
+struct PsfHeader {
+  uint32_t magic;         /* magic bytes to identify PSF */
+  uint32_t version;       /* zero */
+  uint32_t headersize;    /* offset of bitmaps in file, 32 */
+  uint32_t flags;         /* 0 if there's no unicode table */
+  uint32_t numglyph;      /* number of glyphs */
+  uint32_t bytesperglyph; /* size of each glyph */
+  uint32_t height;        /* height in pixels */
+  uint32_t width;         /* width in pixels */
+};
+
+class Psf {
+ public:
+  Psf(OwnedMemoryRegion&& psf_file);
+
+  void DumpHeader();
+
+  uint32_t size() { return header_->numglyph; }
+
+  uint8_t* glyph(uint32_t index) {
+    return reinterpret_cast<uint8_t*>(psf_file_.vaddr() + header_->headersize +
+                                      (index * header_->bytesperglyph));
+  }
+
+ private:
+  OwnedMemoryRegion psf_file_;
+  PsfHeader* header_;
+
+  void EnsureValid();
+};