From 888d289641be21bd50fa56851ca78eb925e2e710 Mon Sep 17 00:00:00 2001
From: Patrick McDermott <patrick.mcdermott@libiquity.com>
Date: Wed, 17 Jul 2019 20:46:07 -0400
Subject: font_render(): Actually address bits in font

---
diff --git a/src/font.c b/src/font.c
index 76510a6..3958891 100644
--- a/src/font.c
+++ b/src/font.c
@@ -21,6 +21,7 @@
 
 #include "font.h"
 
+#include <limits.h>
 #include <string.h>
 
 #include <png.h>
@@ -28,9 +29,12 @@
 #include <linux/font.h>
 #include "image.h"
 
+#define BIT_TO_BYTE(i)         ((i) / CHAR_BIT)
+#define BITS_TO_BYTES(i)       BIT_TO_BYTE((i) + CHAR_BIT - 1)
+#define BIT_BYTE_SHIFT(i)      (CHAR_BIT - 1 - ((i) % CHAR_BIT))
 #define FONT_H(f)              ((size_t) (f)->desc.height)
 #define FONT_W(f)              ((size_t) (f)->desc.width)
-#define CHAR_PIXEL(f, c, x, y) (((((c) * FONT_H(f)) + (y)) * FONT_W(f)) + (x))
+#define FONT_W_BYTES(f)        BITS_TO_BYTES(FONT_W(f))
 
 struct font {
 	const struct font_desc desc;
@@ -76,14 +80,19 @@ void
 font_render(struct font *font, png_const_colorp fg, png_const_colorp bg,
 		char ch, png_bytepp rows, int row, int col)
 {
-	size_t y;
-	size_t r;
-	size_t x;
-	size_t c;
+	size_t        y;
+	size_t        r;
+	size_t        x;
+	size_t        c;
+	size_t        byte;
+	unsigned char font_ch;
 
 	for (y = 0, r = row * FONT_H(font); y < FONT_H(font); ++y, ++r) {
 		for (x = 0, c = col * FONT_W(font); x < FONT_W(font); ++x, ++c){
-			if (CHAR_PIXEL(font, ch, x, y)) {
+			byte = ((ch * FONT_H(font)) + y) * FONT_W_BYTES(font) +
+				BIT_TO_BYTE(x);
+			font_ch = font->desc.data[byte];
+			if ((font_ch >> (BIT_BYTE_SHIFT(x))) & 0x01) {
 				rows[r][c * IMAGE_PIXEL_SIZE + 0] = fg->red;
 				rows[r][c * IMAGE_PIXEL_SIZE + 1] = fg->green;
 				rows[r][c * IMAGE_PIXEL_SIZE + 2] = fg->blue;
--
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