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<Libc>Add-support-for-scanf-accept-formatted-input
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scanf support for multi byte input

Added support for int, long, float, char, string datatype
Added support for value deletion (backspace)

Issue: #225
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@sagarladla
sagarladla committed Jun 28, 2024
1 parent b745155 commit 57413e6
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Showing 2 changed files with 163 additions and 119 deletions.
4 changes: 2 additions & 2 deletions src/lib/libc/include/stdio.h
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Original file line number Diff line number Diff line change
Expand Up @@ -30,17 +30,17 @@ extern FILE stddev[];

int __printf(const char *fmt, ...);
int __eprintf(const char *fmt, ...);
int scanf(const char *fmt, ...);
int fputs(const FILE *, const char *);
int fputc(const FILE *, const char);
int fgetc(const FILE *, char *);
char getch();
char getchar();
char *gets();
int scanf(const char * restrict, ...);

#ifdef _STDBOOL_H_
int fprintf(const FILE *, bool, const char *fmt, ...);
#ifdef _STDARG_H_
int vscanf(const FILE *, const char *fmt, va_list args);
int vprintf(const FILE *, bool, const char *fmt, va_list args);
#endif
#endif
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278 changes: 161 additions & 117 deletions src/lib/libc/scanf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,6 @@
#include <ccpfs.h>
#include <stdio.h>
#include <stddev.h>
#include <stdlib.h>
#include <stdarg.h>
#include <ctype.h>

Expand Down Expand Up @@ -46,155 +45,200 @@ char getchar()
return c;
}

/**
* get string with spaces
*
* @brief This function will take string input with spaces
*
*/
char *gets(char *str)
{
char *p = str;
char temp;
do
{
temp = getch();
fputc(stdout, temp);
if(temp == '\r')
{
fputc(stdout, '\n');
}
else
{
*str++ = temp;
}
} while(temp != '\r');
str = '\0';
return p;
}

/**
* scanf
*
* @brief This function will take standard input for default data types.
* input will break at spaces
*
*/

int scanf(const char * restrict fmt, ...)
int vscanf(const FILE *dev, const char *fmt, va_list args)
{
unsigned int count = 0;
char c = '0', temp;
va_list ap;
va_start(ap, fmt);
while (*fmt)
int ret = 0;
int l_ret;
int N;
char c;
while (*fmt != '\0')
{
l_ret = 0;
if (*fmt == '%')
{
fmt++;
/* char length : %7d */
unsigned int cl = 0;
while (isDigit(*fmt))
loop:
switch (*fmt)
{
cl *= 10;
cl += *fmt++ - '0';
}
switch (*fmt++)
{
case 'c':
case 'i':
case 'd':
{
/* skip leading spaces */
while (isSpace(temp = getch()))
int a = 0;
N = 0;
// skip leading whitespaces
do
{
if (temp == '\r')
fgetc(dev, &c);
if (c == '\r')
fputc(stdout, '\n');
else
fputc(stdout, temp);
}
fputc(stdout, temp);
c = temp;
while ((temp = getch()))
fputc(stdout, c);
} while (isSpace(c));
// initialize first int digit
if (c == '-')
N = 1;
else if (isDigit(c))
a = c - '0';
// append rest of digits till whitespace
do
{
fputc(stdout, temp);
if (isSpace(temp))
break;
}
fputc(stdout, '\n');
*(char *)va_arg(ap, char *) = c;
count++;
fgetc(dev, &c);
if (isDigit(c))
{
a *= 10;
a += (c - '0');
fputc(stdout, c);
}
else if (a && (c == 0x7f || c== 0x08))
{
a /= 10;
fputs(stdout, "\b \b");
}
} while (!isSpace(c));
(c == '\r') ? fputc(stdout, '\n') : fputc(stdout, c);
if (l_ret >= 2)
*(int64_t *)va_arg(args, int64_t *) = (N) ? -(a) : a;
else if (l_ret == 1)
*(long *)va_arg(args, long *) = (N) ? -(a) : a;
else
*(int *)va_arg(args, int *) = (N) ? -(a) : a;
ret++;
break;
}
case 's':
case 'l':
{
char *s = va_arg(ap, char *);
/* skip leading spaces */
while (isSpace(temp = getch()))
l_ret++;
fmt++;
goto loop;
}
#if USE_FLOAT == 1
case 'f':
{
float a = 0;
unsigned int rp = 0; // radix point
float e = 1;
unsigned int fl = 1; // floating length - length after radix point
N = 0;
// skip leading whitespaces
do
{
if (temp == '\r')
fgetc(dev, &c);
if (c == '\r')
fputc(stdout, '\n');
else
fputc(stdout, temp);
}
fputc(stdout, temp);
*s++ = temp;
while ((temp = getch()))
fputc(stdout, c);
} while (isSpace(c));
if (c == '.')
rp = 1;
else if (c == '-')
N = 1;
else if (isDigit(c))
a = (float)(c - '0');
// append rest of digits till whitespace
do
{
fputc(stdout, temp);
if (isSpace(temp))
break;
*s++ = temp;
}
fputc(stdout, '\n');
*s = '\0';
count++;
fgetc(dev, &c);
if (!rp && c == '.')
{
rp = 1;
fputc(stdout, c);
}
else if (isDigit(c))
{
if (rp)
{
e /= 10.0;
a += (e * (float)(c - '0'));
fl *= 10;
}
else
{
a *= 10.0;
a += (float)(c - '0');
}
fputc(stdout, c);
}
else if (a && (c == 0x7f || c == 0x08))
{
long d = (long)a;
float frac = a - (float)d;
if (frac == 0.0 && rp)
rp = 0;
else if (rp)
{
fl /= 10;
frac *= fl;
frac = (long)frac / (float)fl;
a = d + frac;
}
else
a = (int)a / 10;
fputs(stdout, "\b \b");
}
} while (!isSpace(c));
(c == '\r') ? fputc(stdout, '\n') : fputc(stdout, c);
*(float *)va_arg(args, float *) = (N) ? -(a) : a;
ret++;
break;
}
case 'u':
case 'd':
#endif
case 'c':
{
int a = 0;
/* skip leading spaces */
while (isSpace(temp = getch()))
*(char *)va_arg(args, char *) = getchar();
ret++;
break;
}
case 's':
{
int i = 0;
char *s = va_arg(args, char *);
//skip leading whitespaces
do
{
if (temp == '\r')
fgetc(dev, &c);
if (c == '\r')
fputc(stdout, '\n');
else
fputc(stdout, temp);
}
fputc(stdout, temp);
c = temp;
while ((temp = getch()))
fputc(stdout, c);
} while (isSpace(c));
s[i++] = c;
do
{
a *= 10;
if (isDigit(c))
a += (c - '0');
else
a += (int)c;
if (isSpace(temp))
fgetc(dev, &c);
if (isSpace(c))
break;
c = temp;
fputc(stdout, temp);
}
fputc(stdout, '\n');
*(int *)va_arg(ap, int *) = a;
count++;
break;
}
case 'f':
{
char *buff = (char *)malloc(sizeof(char) * 50);
gets(buff);
*(float *)va_arg(ap, float *) = (float)atof(buff);
count++;
else if (i && (c == 0x7f || c == 0x08))
{
i--;
fputs(stdout, "\b \b");
}
else
s[i++] = c;
fputc(stdout, c);
} while (!isSpace(c));
(c == '\r') ? fputc(stdout, '\n') : fputc(stdout, c);
s[i] = '\0';
ret++;
break;
}
default:
break;
return -1;
}
continue;
}
/* increment pointer if % not found */
fmt++;
}
return count;
fputc(stdout, '\n');
return ret;
}

int scanf(const char *fmt, ...)
{
int ret;
va_list va;
va_start(va, fmt);
ret = vscanf(stdin, fmt, va);
va_end(va);
return ret;
}

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