int hd44780_common_redefine_char()

in hd44780_common.c [291:343]

• 36 lines of code
• 8 McCabe index (conditional complexity)

int hd44780_common_redefine_char(struct charlcd *lcd, char *esc)
{
	/* Generator : LGcxxxxx...xx; must have <c> between '0'
	 * and '7', representing the numerical ASCII code of the
	 * redefined character, and <xx...xx> a sequence of 16
	 * hex digits representing 8 bytes for each character.
	 * Most LCDs will only use 5 lower bits of the 7 first
	 * bytes.
	 */

	struct hd44780_common *hdc = lcd->drvdata;
	unsigned char cgbytes[8];
	unsigned char cgaddr;
	int cgoffset;
	int shift;
	char value;
	int addr;

	if (!strchr(esc, ';'))
		return 0;

	esc++;

	cgaddr = *(esc++) - '0';
	if (cgaddr > 7)
		return 1;

	cgoffset = 0;
	shift = 0;
	value = 0;
	while (*esc && cgoffset < 8) {
		int half;

		shift ^= 4;
		half = hex_to_bin(*esc++);
		if (half < 0)
			continue;

		value |= half << shift;
		if (shift == 0) {
			cgbytes[cgoffset++] = value;
			value = 0;
		}
	}

	hdc->write_cmd(hdc, LCD_CMD_SET_CGRAM_ADDR | (cgaddr * 8));
	for (addr = 0; addr < cgoffset; addr++)
		hdc->write_data(hdc, cgbytes[addr]);

	/* ensures that we stop writing to CGRAM */
	lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
	return 1;
}