From 68b5f182af145fdd9e62c9dde3eedcb9108f5ba4 Mon Sep 17 00:00:00 2001
From: Tobias Wiese <tobias@tobiaswiese.com>
Date: Mon, 3 May 2021 23:58:30 +0200
Subject: Initial commit

Signed-off-by: Tobias Wiese <tobias@tobiaswiese.com>
---
 chars/chars.c | 118 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 118 insertions(+)
 create mode 100644 chars/chars.c

(limited to 'chars/chars.c')

diff --git a/chars/chars.c b/chars/chars.c
new file mode 100644
index 0000000..de72a10
--- /dev/null
+++ b/chars/chars.c
@@ -0,0 +1,118 @@
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+
+#include "../libleds.h"
+#include "chars.h"
+
+#include "space.xbm"
+#include "0.xbm"
+#include "1.xbm"
+#include "2.xbm"
+#include "3.xbm"
+#include "4.xbm"
+#include "5.xbm"
+#include "6.xbm"
+#include "7.xbm"
+#include "8.xbm"
+#include "9.xbm"
+
+static unsigned char *get_char_bits(char c) {
+	switch (c) {
+		case ' ':
+			return cspace_bits;
+		case '0':
+			return c0_bits;
+		case '1':
+			return c1_bits;
+		case '2':
+			return c2_bits;
+		case '3':
+			return c3_bits;
+		case '4':
+			return c4_bits;
+		case '5':
+			return c5_bits;
+		case '6':
+			return c6_bits;
+		case '7':
+			return c7_bits;
+		case '8':
+			return c8_bits;
+		case '9':
+			return c9_bits;
+		default:
+			return NULL;
+	}
+}
+
+static char is_active(unsigned char const *bits, unsigned int const i)
+{
+	/*
+	 * The first led is in the top left corner.
+	 * After that it goes down the column, then up the next and so on.
+	 *
+	 * This means all columns with an even index count down.
+	 * Those with an odd index count up.
+	 *
+	 *
+	 * With a height of 8 the led numbers would look like this:
+	 *
+	 * 00  0F  10  1F  20  ...
+	 * 01  0E  11  1E  21  ...
+	 * 02  0D  12  1D  ...
+	 * 03  0C  13  1C  ...
+	 * 04  0B  14  1B  ...
+	 * 05  0A  15  1A  ...
+	 * 06  09  16  19  ...
+	 * 07  08  17  18  ...
+	 */
+
+	unsigned int const bytes_per_row = ceil(char_width / 8.0);
+	unsigned int col = i / char_height;
+	unsigned int row = i % char_height;
+	if (col % 2)
+		row = char_height - 1 - row;
+	
+	// calculate byte to access
+	unsigned int byte = row * bytes_per_row;
+	byte += col / 8;
+
+	unsigned char data = bits[byte];
+	unsigned char mask = 1<<(col % 8);
+	return data & mask;
+}
+
+static char leds_write_char(const struct led_color color, char c, struct led_color *buf)
+{
+	unsigned char *bits = get_char_bits(c);
+	if (bits == NULL)
+		return 0;
+
+	for (unsigned int i = 0; i < char_length; i++) {
+		if (is_active(bits, i))
+			buf[i] = color;
+		else
+			buf[i] = (struct led_color){0, 0, 0};
+	}
+
+	return 1;
+}
+
+struct led_color *leds_text(struct led_color const color, const char *text)
+{
+	unsigned int const len = strlen(text);
+	struct led_color *buf = calloc(
+		sizeof(struct led_color), len * char_length
+	);
+
+	for (unsigned int i = 0; i < len; i++) {
+		if (!leds_write_char(color, text[i], buf + i*char_length)) {
+			// Invalid char
+			free(buf);
+			return NULL;
+		}
+	}
+
+	return buf;
+}
-- 
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