docs/feature_hd44780.md


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# HD44780 LCD Displays

This is an integration of Peter Fleury's LCD library. This page will explain the basics. [For in depth documentation visit his page.](http://www.peterfleury.epizy.com/doxygen/avr-gcc-libraries/group__pfleury__lcd.html)

You can enable support for HD44780 Displays by setting the `HD44780_ENABLE` flag in your keyboards `rules.mk` to yes.

## Configuration

You will need to configure the pins used by your display, and its number of lines and columns in your keyboard's `config.h`.


Uncomment the section labled HD44780 and change the parameters as needed.
````
/*
 * HD44780 LCD Display Configuration
 */

#define LCD_LINES           2     //< number of visible lines of the display
#define LCD_DISP_LENGTH    16     //< visibles characters per line of the display
#define LCD_IO_MODE      1            //< 0: memory mapped mode, 1: IO port mode
#if LCD_IO_MODE
#define LCD_PORT         PORTB        //< port for the LCD lines
#define LCD_DATA0_PORT   LCD_PORT     //< port for 4bit data bit 0
#define LCD_DATA1_PORT   LCD_PORT     //< port for 4bit data bit 1
#define LCD_DATA2_PORT   LCD_PORT     //< port for 4bit data bit 2
#define LCD_DATA3_PORT   LCD_PORT     //< port for 4bit data bit 3
#define LCD_DATA0_PIN    4            //< pin for 4bit data bit 0
#define LCD_DATA1_PIN    5            //< pin for 4bit data bit 1
#define LCD_DATA2_PIN    6            //< pin for 4bit data bit 2
#define LCD_DATA3_PIN    7            //< pin for 4bit data bit 3
#define LCD_RS_PORT      LCD_PORT     //< port for RS line        
#define LCD_RS_PIN       3            //< pin  for RS line        
#define LCD_RW_PORT      LCD_PORT     //< port for RW line        
#define LCD_RW_PIN       2            //< pin  for RW line        
#define LCD_E_PORT       LCD_PORT     //< port for Enable line     
#define LCD_E_PIN        1            //< pin  for Enable line    
#endif
````

Should you need to configure other properties you can copy them from `quantum/hd44780.h` and set them in your `config.h`

## Usage

To initialize your display, call `lcd_init()` with one of these parameters:
````
LCD_DISP_OFF             : display off
LCD_DISP_ON              : display on, cursor off
LCD_DISP_ON_CURSOR       : display on, cursor on
LCD_DISP_ON_CURSOR_BLINK : display on, cursor on flashing
````
This is best done in your keyboards `matrix_init_kb` or your keymaps `matrix_init_user`.  
It is advised to clear the display before use.  
To do so call `lcd_clrscr()`.

To now print something to your Display you first call `lcd_gotoxy(column, line)`. To go to the start of the first line you would call `lcd_gotoxy(0, 0)` and then print a string with `lcd_puts("example string")`.

There are more methods available to control the display. [For in depth documentation please visit the linked page.](http://www.peterfleury.epizy.com/doxygen/avr-gcc-libraries/group__pfleury__lcd.html)
/*
 ****************************************************************************
 * (C) 2003 - Rolf Neugebauer - Intel Research Cambridge
 ****************************************************************************
 *
 *        File: printf.c
 *      Author: Rolf Neugebauer (neugebar@dcs.gla.ac.uk)
 *     Changes: Grzegorz Milos (gm281@cam.ac.uk) 
 *
 *        Date: Aug 2003, Aug 2005
 *
 * Environment: Xen Minimal OS
 * Description: Library functions for printing
 *              (Linux port, mainly lib/vsprintf.c)
 *
 ****************************************************************************
 */

/*
 * Copyright (C) 1991, 1992  Linus Torvalds
 */

/* vsprintf.c -- Lars Wirzenius & Linus Torvalds. */
/*
 * Wirzenius wrote this portably, Torvalds fucked it up :-)
 */

/*
 * Fri Jul 13 2001 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
 * - changed to provide snprintf and vsnprintf functions
 * So Feb  1 16:51:32 CET 2004 Juergen Quade <quade@hsnr.de>
 * - scnprintf and vscnprintf
 *
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#if !defined HAVE_LIBC

#include <mini-os/os.h>
#include <mini-os/types.h>
#include <mini-os/hypervisor.h>
#include <mini-os/lib.h>
#include <mini-os/mm.h>
#include <mini-os/ctype.h>
#include <mini-os/posix/limits.h>

/**
 * simple_strtoul - convert a string to an unsigned long
 * @cp: The start of the string
 * @endp: A pointer to the end of the parsed string will be placed here
 * @base: The number base to use
 */
unsigned long simple_strtoul(const char *cp,char **endp,unsigned int base)
{
    unsigned long result = 0,value;

    if (!base) {
        base = 10;
        if (*cp == '0') {
            base = 8;
            cp++;
            if ((*cp == 'x') && isxdigit(cp[1])) {
                cp++;
                base = 16;
            }
        }
    }
    while (isxdigit(*cp) &&
           (value = isdigit(*cp) ? *cp-'0' : toupper(*cp)-'A'+10) < base) {
        result = result*base + value;
        cp++;
    }
    if (endp)
        *endp = (char *)cp;
    return result;
}

/**
 * simple_strtol - convert a string to a signed long
 * @cp: The start of the string
 * @endp: A pointer to the end of the parsed string will be placed here
 * @base: The number base to use
 */
long simple_strtol(const char *cp,char **endp,unsigned int base)
{
    if(*cp=='-')
        return -simple_strtoul(cp+1,endp,base);
    return simple_strtoul(cp,endp,base);
}

/**
 * simple_strtoull - convert a string to an unsigned long long
 * @cp: The start of the string
 * @endp: A pointer to the end of the parsed string will be placed here
 * @base: The number base to use
 */
unsigned long long simple_strtoull(const char *cp,char **endp,unsigned int base)
{
    unsigned long long result = 0,value;

    if (!base) {
        base = 10;
        if (*cp == '0') {
            base = 8;
            cp++;
            if ((*cp == 'x') && isxdigit(cp[1])) {
                cp++;
                base = 16;
            }
        }
    }
    while (isxdigit(*cp) && (value = isdigit(*cp) ? *cp-'0' : (islower(*cp)
                                                               ? toupper(*cp) : *cp)-'A'+10) < base) {
        result = result*base + value;
        cp++;
    }
    if (endp)
        *endp = (char *)cp;
    return result;
}

/**
 * simple_strtoll - convert a string to a signed long long
 * @cp: The start of the string
 * @endp: A pointer to the end of the parsed string will be placed here
 * @base: The number base to use
 */
long long simple_strtoll(const char *cp,char **endp,unsigned int base)
{
    if(*cp=='-')
        return -simple_strtoull(cp+1,endp,base);
    return simple_strtoull(cp,endp,base);
}

static int skip_atoi(const char **s)
{
    int i=0;

    while (isdigit(**s))
        i = i*10 + *((*s)++) - '0';
    return i;
}

#define ZEROPAD 1               /* pad with zero */
#define SIGN    2               /* unsigned/signed long */
#define PLUS    4               /* show plus */
#define SPACE   8               /* space if plus */
#define LEFT    16              /* left justified */
#define SPECIAL 32              /* 0x */
#define LARGE   64              /* use 'ABCDEF' instead of 'abcdef' */

static char * number(char * buf, char * end, long long num, int base, int size, int precision, int type)
{
    char c,sign,tmp[66];
    const char *digits;
    const char small_digits[] = "0123456789abcdefghijklmnopqrstuvwxyz";
    const char large_digits[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    int i;

    digits = (type & LARGE) ? large_digits : small_digits;
    if (type & LEFT)
        type &= ~ZEROPAD;
    if (base < 2 || base > 36)
        return buf;
    c = (type & ZEROPAD) ? '0' : ' ';
    sign = 0;
    if (type & SIGN) {
        if (num < 0) {
            sign = '-';
            num = -num;
            size--;
        } else if (type & PLUS) {
            sign = '+';
            size--;
        } else if (type & SPACE) {
            sign = ' ';
            size--;
        }
    }
    if (type & SPECIAL) {
        if (base == 16)
            size -= 2;
        else if (base == 8)
            size--;
    }
    i = 0;
    if (num == 0)
        tmp[i++]='0';
    else 
    {
        /* XXX KAF: force unsigned mod and div. */
        unsigned long long num2=(unsigned long long)num;
        unsigned int base2=(unsigned int)base;
        while (num2 != 0) { tmp[i++] = digits[num2%base2]; num2 /= base2; }
    }
    if (i > precision)
        precision = i;
    size -= precision;
    if (!(type&(ZEROPAD+LEFT))) {
        while(size-->0) {
            if (buf <= end)
                *buf = ' ';
            ++buf;
        }
    }
    if (sign) {
        if (buf <= end)
            *buf = sign;
        ++buf;
    }
    if (type & SPECIAL) {
        if (base==8) {
            if (buf <= end)
                *buf = '0';
            ++buf;
        } else if (base==16) {
            if (buf <= end)
                *buf = '0';
            ++buf;
            if (buf <= end)
                *buf = digits[33];
            ++buf;
        }
    }
    if (!(type & LEFT)) {
        while (size-- > 0) {
            if (buf <= end)
                *buf = c;
            ++buf;
        }
    }
    while (i < precision--) {
        if (buf <= end)
            *buf = '0';
        ++buf;
    }
    while (i-- > 0) {
        if (buf <= end)
            *buf = tmp[i];
        ++buf;
    }
    while (size-- > 0) {
        if (buf <= end)
            *buf = ' ';
        ++buf;
    }
    return buf;
}

/**
* vsnprintf - Format a string and place it in a buffer
* @buf: The buffer to place the result into
* @size: The size of the buffer, including the trailing null space
* @fmt: The format string to use
* @args: Arguments for the format string
*
* Call this function if you are already dealing with a va_list.
* You probably want snprintf instead.
 */
int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
{
    int len;
    unsigned long long num;
    int i, base;
    char *str, *end, c;
    const char *s;

    int flags;          /* flags to number() */

    int field_width;    /* width of output field */
    int precision;              /* min. # of digits for integers; max
                                   number of chars for from string */
    int qualifier;              /* 'h', 'l', or 'L' for integer fields */
                                /* 'z' support added 23/7/1999 S.H.    */
                                /* 'z' changed to 'Z' --davidm 1/25/99 */

    str = buf;
    end = buf + size - 1;

    if (end < buf - 1) {
        end = ((void *) -1);
        size = end - buf + 1;
    }

    for (; *fmt ; ++fmt) {
        if (*fmt != '%') {
            if (str <= end)
                *str = *fmt;
            ++str;
            continue;
        }

        /* process flags */
        flags = 0;
    repeat:
        ++fmt;          /* this also skips first '%' */
        switch (*fmt) {
        case '-': flags |= LEFT; goto repeat;
        case '+': flags |= PLUS; goto repeat;
        case ' ': flags |= SPACE; goto repeat;
        case '#': flags |= SPECIAL; goto repeat;
        case '0': flags |= ZEROPAD; goto repeat;
        }

        /* get field width */
        field_width = -1;
        if (isdigit(*fmt))
            field_width = skip_atoi(&fmt);
        else if (*fmt == '*') {
            ++fmt;
            /* it's the next argument */
            field_width = va_arg(args, int);
            if (field_width < 0) {
                field_width = -field_width;
                flags |= LEFT;
            }
        }

        /* get the precision */
        precision = -1;
        if (*fmt == '.') {
            ++fmt;
            if (isdigit(*fmt))
                precision = skip_atoi(&fmt);
            else if (*fmt == '*') {
                ++fmt;
                          /* it's the next argument */
                precision = va_arg(args, int);
            }
            if (precision < 0)
                precision = 0;
        }

        /* get the conversion qualifier */
        qualifier = -1;
        if (*fmt == 'h' || *fmt == 'l' || *fmt == 'L' || *fmt =='Z') {
            qualifier = *fmt;
            ++fmt;
            if (qualifier == 'l' && *fmt == 'l') {
                qualifier = 'L';
                ++fmt;
            }
        }
        if (*fmt == 'q') {
            qualifier = 'L';
            ++fmt;
        }

        /* default base */
        base = 10;

        switch (*fmt) {
        case 'c':
            if (!(flags & LEFT)) {
                while (--field_width > 0) {
                    if (str <= end)
                        *str = ' ';
                    ++str;
                }
            }
            c = (unsigned char) va_arg(args, int);
            if (str <= end)
                *str = c;
            ++str;
            while (--field_width > 0) {
                if (str <= end)
                    *str = ' ';
                ++str;
            }
            continue;

        case 's':
            s = va_arg(args, char *);
            if (!s)
                s = "<NULL>";

            len = strnlen(s, precision);

            if (!(flags & LEFT)) {
                while (len < field_width--) {
                    if (str <= end)
                        *str = ' ';
                    ++str;
                }
            }
            for (i = 0; i < len; ++i) {
                if (str <= end)
                    *str = *s;
                ++str; ++s;
            }
            while (len < field_width--) {
                if (str <= end)
                    *str = ' ';
                ++str;
            }
            continue;

        case 'p':
            if (field_width == -1) {
                field_width = 2*sizeof(void *);
                flags |= ZEROPAD;
            }
            str = number(str, end,
                         (unsigned long) va_arg(args, void *),
                         16, field_width, precision, flags);
            continue;


        case 'n':
            if (qualifier == 'l') {
                long * ip = va_arg(args, long *);
                *ip = (str - buf);
            } else if (qualifier == 'Z') {
                size_t * ip = va_arg(args, size_t *);
                *ip = (str - buf);
            } else {
                int * ip = va_arg(args, int *);
                *ip = (str - buf);
            }
            continue;

        case '%':
            if (str <= end)
                *str = '%';
            ++str;
            continue;

            /* integer number formats - set up the flags and "break" */
        case 'o':
            base = 8;
            break;

        case 'X':
            flags |= LARGE;
        case 'x':
            base = 16;
            break;

        case 'd':
        case 'i':
            flags |= SIGN;
        case 'u':
            break;

        default:
            if (str <= end)
                *str = '%';
            ++str;
            if (*fmt) {
                if (str <= end)
                    *str = *fmt;
                ++str;
            } else {
                --fmt;
            }
            continue;
        }
        if (qualifier == 'L')
            num = va_arg(args, long long);
        else if (qualifier == 'l') {
            num = va_arg(args, unsigned long);
            if (flags & SIGN)
                num = (signed long) num;
        } else if (qualifier == 'Z') {
            num = va_arg(args, size_t);
        } else if (qualifier == 'h') {
            num = (unsigned short) va_arg(args, int);
            if (flags & SIGN)
                num = (signed short) num;
        } else {
            num = va_arg(args, unsigned int);
            if (flags & SIGN)
                num = (signed int) num;
        }

        str = number(str, end, num, base,
                     field_width, precision, flags);
    }
    if (str <= end)
        *str = '\0';
    else if (size > 0)
        /* don't write out a null byte if the buf size is zero */
        *end = '\0';
    /* the trailing null byte doesn't count towards the total
     * ++str;
     */
    return str-buf;
}

/**
 * snprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @size: The size of the buffer, including the trailing null space
 * @fmt: The format string to use
 * @...: Arguments for the format string
 */
int snprintf(char * buf, size_t size, const char *fmt, ...)
{
    va_list args;
    int i;

    va_start(args, fmt);
    i=vsnprintf(buf,size,fmt,args);
    va_end(args);
    return i;
}

/**
 * vsprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @fmt: The format string to use
 * @args: Arguments for the format string
 *
 * Call this function if you are already dealing with a va_list.
 * You probably want sprintf instead.
 */
int vsprintf(char *buf, const char *fmt, va_list args)
{
    return vsnprintf(buf, 0xFFFFFFFFUL, fmt, args);
}


/**
 * sprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @fmt: The format string to use
 * @...: Arguments for the format string
 */
int sprintf(char * buf, const char *fmt, ...)
{
    va_list args;
    int i;

    va_start(args, fmt);
    i=vsprintf(buf,fmt,args);
    va_end(args);
    return i;
}

/**
 * vsscanf - Unformat a buffer into a list of arguments
 * @buf:	input buffer
 * @fmt:	format of buffer
 * @args:	arguments
 */
int vsscanf(const char * buf, const char * fmt, va_list args)
{
	const char *str = buf;
	char *next;
	char digit;
	int num = 0;
	int qualifier;
	int base;
	int field_width;
	int is_sign = 0;

	while(*fmt && *str) {
		/* skip any white space in format */
		/* white space in format matchs any amount of
		 * white space, including none, in the input.
		 */
		if (isspace(*fmt)) {
			while (isspace(*fmt))
				++fmt;
			while (isspace(*str))
				++str;
		}

		/* anything that is not a conversion must match exactly */
		if (*fmt != '%' && *fmt) {
			if (*fmt++ != *str++)
				break;
			continue;
		}

		if (!*fmt)
			break;
		++fmt;
		
		/* skip this conversion.
		 * advance both strings to next white space
		 */
		if (*fmt == '*') {
			while (!isspace(*fmt) && *fmt)
				fmt++;
			while (!isspace(*str) && *str)
				str++;
			continue;
		}

		/* get field width */
		field_width = -1;
		if (isdigit(*fmt))
			field_width = skip_atoi(&fmt);

		/* get conversion qualifier */
		qualifier = -1;
		if (*fmt == 'h' || *fmt == 'l' || *fmt == 'L' ||
		    *fmt == 'Z' || *fmt == 'z') {
			qualifier = *fmt++;
			if (unlikely(qualifier == *fmt)) {
				if (qualifier == 'h') {
					qualifier = 'H';
					fmt++;
				} else if (qualifier == 'l') {
					qualifier = 'L';
					fmt++;
				}
			}
		}
		base = 10;
		is_sign = 0;

		if (!*fmt || !*str)
			break;

		switch(*fmt++) {
		case 'c':
		{
			char *s = (char *) va_arg(args,char*);
			if (field_width == -1)
				field_width = 1;
			do {
				*s++ = *str++;
			} while (--field_width > 0 && *str);
			num++;
		}
		continue;
		case 's':
		{
			char *s = (char *) va_arg(args, char *);
			if(field_width == -1)
				field_width = INT_MAX;
			/* first, skip leading white space in buffer */
			while (isspace(*str))
				str++;

			/* now copy until next white space */
			while (*str && !isspace(*str) && field_width--) {
				*s++ = *str++;
			}
			*s = '\0';
			num++;
		}
		continue;
		case 'n':
			/* return number of characters read so far */
		{
			int *i = (int *)va_arg(args,int*);
			*i = str - buf;
		}
		continue;
		case 'o':
			base = 8;
			break;
		case 'x':
		case 'X':
			base = 16;
			break;
		case 'i':
                        base = 0;
		case 'd':
			is_sign = 1;
		case 'u':
			break;
		case '%':
			/* looking for '%' in str */
			if (*str++ != '%') 
				return num;
			continue;
		default:
			/* invalid format; stop here */
			return num;
		}

		/* have some sort of integer conversion.
		 * first, skip white space in buffer.
		 */
		while (isspace(*str))
			str++;

		digit = *str;
		if (is_sign && digit == '-')
			digit = *(str + 1);

		if (!digit
                    || (base == 16 && !isxdigit(digit))
                    || (base == 10 && !isdigit(digit))
                    || (base == 8 && (!isdigit(digit) || digit > '7'))
                    || (base == 0 && !isdigit(digit)))
				break;

		switch(qualifier) {
		case 'H':	/* that's 'hh' in format */
			if (is_sign) {
				signed char *s = (signed char *) va_arg(args,signed char *);
				*s = (signed char) simple_strtol(str,&next,base);
			} else {
				unsigned char *s = (unsigned char *) va_arg(args, unsigned char *);
				*s = (unsigned char) simple_strtoul(str, &next, base);
			}
			break;
		case 'h':
			if (is_sign) {
				short *s = (short *) va_arg(args,short *);
				*s = (short) simple_strtol(str,&next,base);
			} else {
				unsigned short *s = (unsigned short *) va_arg(args, unsigned short *);
				*s = (unsigned short) simple_strtoul(str, &next, base);
			}
			break;
		case 'l':
			if (is_sign) {
				long *l = (long *) va_arg(args,long *);
				*l = simple_strtol(str,&next,base);
			} else {
				unsigned long *l = (unsigned long*) va_arg(args,unsigned long*);
				*l = simple_strtoul(str,&next,base);
			}
			break;
		case 'L':
			if (is_sign) {
				long long *l = (long long*) va_arg(args,long long *);
				*l = simple_strtoll(str,&next,base);
			} else {
				unsigned long long *l = (unsigned long long*) va_arg(args,unsigned long long*);
				*l = simple_strtoull(str,&next,base);
			}
			break;
		case 'Z':
		case 'z':
		{
			size_t *s = (size_t*) va_arg(args,size_t*);
			*s = (size_t) simple_strtoul(str,&next,base);
		}
		break;
		default:
			if (is_sign) {
				int *i = (int *) va_arg(args, int*);
				*i = (int) simple_strtol(str,&next,base);
			} else {
				unsigned int *i = (unsigned int*) va_arg(args, unsigned int*);
				*i = (unsigned int) simple_strtoul(str,&next,base);
			}
			break;
		}
		num++;

		if (!next)
			break;
		str = next;
	}
	return num;
}

/**
 * sscanf - Unformat a buffer into a list of arguments
 * @buf:	input buffer
 * @fmt:	formatting of buffer
 * @...:	resulting arguments
 */
int sscanf(const char * buf, const char * fmt, ...)
{
	va_list args;
	int i;

	va_start(args,fmt);
	i = vsscanf(buf,fmt,args);
	va_end(args);
	return i;
}

#endif