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#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdarg.h>
int putchar(int character)
{
char byte = (char)character;
if (write(1, &byte, 1) != 1)
return EOF;
return (unsigned char)byte;
}
int getchar(void)
{
char byte;
if (read(0, &byte, 1) <= 0)
return EOF;
return (unsigned char)byte;
}
int puts(const char* string)
{
(void)write(1, string, strlen(string));
(void)write(1, "\n", 1);
return 0;
}
static int format_unsigned(char* buffer, unsigned long value, int base, int upper)
{
const char* digits = upper ? "0123456789ABCDEF" : "0123456789abcdef";
char temp[32];
int count = 0;
if (value == 0)
temp[count++] = '0';
while (value > 0)
{
temp[count++] = digits[value % (unsigned)base];
value /= (unsigned)base;
}
for (int i = 0; i < count; i++)
buffer[i] = temp[count - 1 - i];
return count;
}
static int format_signed(char* buffer, long value)
{
int negative = value < 0;
unsigned long magnitude = negative ? (unsigned long)(-value) : (unsigned long)value;
int count = 0;
if (negative)
buffer[count++] = '-';
return count + format_unsigned(buffer + count, magnitude, 10, 0);
}
#define PRINTF_BUFFER 256
// yoinked straight off open source
int printf(const char* format, ...)
{
char out[PRINTF_BUFFER];
int filled = 0;
int total = 0;
va_list args;
va_start(args, format);
#define FLUSH() \
do { \
if (filled > 0) \
{ \
(void)write(1, out, filled); \
filled = 0; \
} \
} while (0)
#define EMIT(ch) \
do { \
if (filled == PRINTF_BUFFER) \
FLUSH(); \
out[filled++] = (char)(ch); \
total++; \
} while (0)
for (const char* cursor = format; *cursor; cursor++)
{
if (*cursor != '%')
{
EMIT(*cursor);
continue;
}
cursor++;
if (*cursor == '%')
{
EMIT('%');
continue;
}
int zero_pad = 0;
if (*cursor == '0')
{
zero_pad = 1;
cursor++;
}
int width = 0;
while (*cursor >= '0' && *cursor <= '9')
{
width = width * 10 + (*cursor - '0');
cursor++;
}
int is_long = 0;
while (*cursor == 'l')
{
is_long = 1;
cursor++;
}
char conversion = *cursor;
if (conversion == 's')
{
const char* string = va_arg(args, const char*);
if (!string)
string = "(null)";
int length = (int)strlen(string);
for (int i = length; i < width; i++)
EMIT(' ');
for (int i = 0; i < length; i++)
EMIT(string[i]);
continue;
}
if (conversion == 'c')
{
int character = va_arg(args, int);
for (int i = 1; i < width; i++)
EMIT(' ');
EMIT(character);
continue;
}
char number[34];
int length = 0;
if (conversion == 'd' || conversion == 'i')
{
long value = is_long ? va_arg(args, long) : (long)va_arg(args, int);
length = format_signed(number, value);
}
else if (conversion == 'u')
{
unsigned long value = is_long ? va_arg(args, unsigned long) : (unsigned long)va_arg(args, unsigned int);
length = format_unsigned(number, value, 10, 0);
}
else if (conversion == 'x' || conversion == 'X')
{
unsigned long value = is_long ? va_arg(args, unsigned long) : (unsigned long)va_arg(args, unsigned int);
length = format_unsigned(number, value, 16, conversion == 'X');
}
else if (conversion == 'p')
{
unsigned long value = (unsigned long)va_arg(args, void*);
EMIT('0');
EMIT('x');
length = format_unsigned(number, value, 16, 0);
}
else
{
EMIT('%');
EMIT(conversion);
continue;
}
for (int i = length; i < width; i++)
EMIT(zero_pad ? '0' : ' ');
for (int i = 0; i < length; i++)
EMIT(number[i]);
}
FLUSH();
va_end(args);
return total;
#undef EMIT
#undef FLUSH
}
int readline(char* buffer, int max_length)
{
int length = 0;
for (;;)
{
char character;
if (read(0, &character, 1) <= 0)
break;
if (character == '\n')
break;
if (character == '\b')
{
if (length > 0)
{
length--;
(void)write(1, "\b \b", 3);
}
continue;
}
if (length < max_length - 1)
{
buffer[length++] = character;
(void)write(1, &character, 1);
}
}
buffer[length] = 0;
return length;
}
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