fonts: put rendering into a function

1 files changed, 27 insertions, 0 deletions

diff --git a/fonts.c b/fonts.c
new file mode 100644
index 0000000..f72f38c
--- /dev/null
+++ b/fonts.c
@@ -0,0 +1,27 @@
+#include <string.h>
+
+#include "fonts.h"
+
+void render(unsigned char *input, int input_len, unsigned char *output, int max_output_len, int skip_unprintables)
+{
+  memset(output, 0, max_output_len);
+  int output_i = 0;
+  for (int input_i=0; (input_i < input_len) && (output_i*(SYMBOL_WIDTH+1) < max_output_len); input_i++) {
+    unsigned char c = input[input_i];
+    if (c >= 0x7f) {
+      if (c <= 0xaf) {
+        output_i += !!skip_unprintables;
+        continue;
+      }
+      c -= 0xaf - 0x7f + 1;
+    }
+    c -= 0x20;
+    if ((c < 0) || (c >= (sizeof(symbols) / SYMBOL_WIDTH))) {
+      output_i += !!skip_unprintables;
+      continue;
+    }
+    for (int i=0; (i<SYMBOL_WIDTH) && (output_i*(SYMBOL_WIDTH+1) + i < max_output_len); i++)
+      output[output_i*(SYMBOL_WIDTH+1) + i] = symbols[c*SYMBOL_WIDTH + i];
+    output_i++;
+  }
+}