[Teton] Factor drawing glyphs to screen into a separate class.

sys/teton/CMakeLists.txt

@@ -1,4 +1,5 @@
 add_executable(teton
+  framebuffer/console.cpp
   framebuffer/framebuffer.cpp
   framebuffer/psf.cpp
   teton.cpp

sys/teton/framebuffer/console.cpp

@@ -0,0 +1,28 @@
+#include "framebuffer/console.h"
+
+void Console::WriteChar(char c) {
+  uint64_t row = cursor_pos_ / cols();
+  uint64_t fb_row = row * (psf_.height() + 1);
+  uint64_t col = cursor_pos_ % cols();
+  uint64_t fb_col = col * (psf_.width() + 1);
+
+  uint8_t* glyph = psf_.glyph(c);
+
+  for (uint8_t r = fb_row; r < fb_row + psf_.height(); r++) {
+    for (uint8_t c = fb_col; c < fb_col + psf_.width(); c++) {
+      uint8_t glyph_offset = psf_.width() - (c - fb_col) - 1;
+      if ((glyph[r] & (1 << glyph_offset))) {
+        framebuf_.DrawPixel(r, c, 0xFFFFFFF);
+      } else {
+        framebuf_.DrawPixel(r, c, 0);
+      }
+    }
+  }
+
+  cursor_pos_++;
+}
+void Console::WriteString(glcr::StringView str) {
+  for (uint64_t i = 0; i < str.size(); i++) {
+    WriteChar(str[i]);
+  }
+}

sys/teton/framebuffer/console.h

@@ -0,0 +1,23 @@
+#pragma once
+
+#include <glacier/string/string_view.h>
+
+#include "framebuffer/framebuffer.h"
+#include "framebuffer/psf.h"
+
+class Console {
+ public:
+  explicit Console(Framebuffer& fb, Psf& psf) : framebuf_(fb), psf_(psf) {}
+
+  void WriteChar(char c);
+  void WriteString(glcr::StringView str);
+
+  uint32_t rows() { return framebuf_.height() / (psf_.height() + 1); }
+  uint32_t cols() { return framebuf_.width() / (psf_.width() + 1); }
+
+ private:
+  // TODO: Don't store a reference here.
+  Framebuffer& framebuf_;
+  Psf& psf_;
+  uint64_t cursor_pos_ = 0;
+};

sys/teton/framebuffer/framebuffer.h

@@ -11,6 +11,9 @@ class Framebuffer {
 
   void DrawGlyph(uint8_t* glyph);
 
+  uint64_t width() { return fb_info_.width(); }
+  uint64_t height() { return fb_info_.height(); }
+
  private:
   // FIXME: Implement Yunq copy or move so we
   // don't have to store a reference here.

sys/teton/framebuffer/psf.h

@@ -20,6 +20,8 @@ class Psf {
   void DumpHeader();
 
   uint32_t size() { return header_->numglyph; }
+  uint32_t width() { return header_->width; }
+  uint32_t height() { return header_->height; }
 
   uint8_t* glyph(uint32_t index) {
     return reinterpret_cast<uint8_t*>(psf_file_.vaddr() + header_->headersize +

sys/teton/teton.cpp

@@ -3,6 +3,7 @@
 #include <victoriafalls/victoriafalls.yunq.client.h>
 #include <yellowstone/yellowstone.yunq.client.h>
 
+#include "framebuffer/console.h"
 #include "framebuffer/framebuffer.h"
 #include "framebuffer/psf.h"
 
@@ -22,12 +23,6 @@ uint64_t main(uint64_t init_port) {
 
   Framebuffer fbuf(framebuffer);
 
-  for (uint64_t r = 0; r < 20; r++) {
-    for (uint64_t c = 0; c < 20; c++) {
-      fbuf.DrawPixel(r, c, 0x0000FF00);
-    }
-  }
-
   // 2. Parse a font file.
 
   GetEndpointRequest req;
@@ -45,7 +40,8 @@ uint64_t main(uint64_t init_port) {
   Psf psf(OwnedMemoryRegion::FromCapability(fresp.memory()));
   psf.DumpHeader();
 
-  fbuf.DrawGlyph(psf.glyph('C'));
+  Console console(fbuf, psf);
+  console.WriteString("Hello World!");
 
   // 3. Write a line to the screen.