forked from Bananymous/banan-os
342 lines
6.8 KiB
C++
342 lines
6.8 KiB
C++
#include <ctype.h>
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#include <errno.h>
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#include <stdio.h>
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#include <string.h>
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#define BAN_PRINTF_PUTC(c) \
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do \
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{ \
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if (putc_fun((c), data) == EOF) \
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return -1; \
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written++; \
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} while (false)
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struct format_options_t
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{
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bool alternate_form { false };
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bool zero_padded { false };
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bool left_justified { false };
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bool show_plus_sign_as_space { false };
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bool show_plus_sign { false };
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int width { -1 };
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int percision { -1 };
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};
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template<typename T>
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static void integer_to_string(char* buffer, T value, int base, bool upper, const format_options_t options)
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{
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int width = 1;
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bool zero_padded = options.zero_padded;
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if (options.percision != -1)
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{
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width = options.percision;
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zero_padded = false;
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}
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else if (options.width != -1)
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width = options.width;
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auto digit_char = [](int digit, bool upper)
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{
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if (digit < 10)
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return '0' + digit;
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return (upper ? 'A' : 'a') + (digit - 10);
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};
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bool sign = false;
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int offset = 0;
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if (value < 0)
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{
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sign = true;
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buffer[offset++] = digit_char(-(value % base), upper);
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value = -(value / base);
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}
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while (value)
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{
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buffer[offset++] = digit_char(value % base, upper);
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value /= base;
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}
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int prefix_length = 0;
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if (sign || options.show_plus_sign || options.show_plus_sign_as_space)
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prefix_length++;
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if (base == 8 && options.alternate_form)
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prefix_length++;
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if (base == 16 && options.alternate_form)
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prefix_length += 2;
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while (offset < width - prefix_length)
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buffer[offset++] = (zero_padded ? '0' : ' ');
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if (sign)
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buffer[offset++] = '-';
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else if (options.show_plus_sign)
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buffer[offset++] = '+';
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else if (options.show_plus_sign_as_space)
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buffer[offset++] = ' ';
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if (base == 8 && options.alternate_form)
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buffer[offset++] = '0';
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if (base == 16 && options.alternate_form)
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{
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buffer[offset++] = 'x';
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buffer[offset++] = '0';
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}
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for (int i = 0; i < offset / 2; i++)
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{
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char temp = buffer[i];
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buffer[i] = buffer[offset - i - 1];
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buffer[offset - i - 1] = temp;
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}
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buffer[offset++] = '\0';
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}
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template<typename T>
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static void floating_point_to_exponent_string(char* buffer, T value, bool upper, const format_options_t options)
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{
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int percision = 6;
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if (options.percision != -1)
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percision = options.percision;
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strcpy(buffer, "??e??");
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}
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template<typename T>
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static void floating_point_to_string(char* buffer, T value, bool upper, const format_options_t options)
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{
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int percision = 6;
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if (options.percision != -1)
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percision = options.percision;
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strcpy(buffer, "??.??");
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}
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extern "C" int printf_impl(const char* format, va_list arguments, int (*putc_fun)(int, void*), void* data)
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{
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int written = 0;
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while (*format)
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{
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if (*format == '%')
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{
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format_options_t options;
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// PARSE FLAGS
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bool flags_done = false;
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while (!flags_done)
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{
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format++;
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switch (*format)
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{
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case '#': options.alternate_form = true; break;
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case '0': options.zero_padded = true; break;
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case '-': options.left_justified = true; break;
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case ' ': options.show_plus_sign_as_space = true; break;
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case '+': options.show_plus_sign = true; break;
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default:
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flags_done = true;
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break;
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}
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}
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if (options.zero_padded && options.left_justified)
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options.zero_padded = false;
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// PARSE FIELD WIDTH
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if (*format == '*')
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{
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options.width = va_arg(arguments, int);
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format++;
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}
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else if (isdigit(*format) && *format != '0')
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{
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int width = 0;
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while (isdigit(*format))
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{
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width *= 10;
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width += *format - '0';
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format++;
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}
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options.width = width;
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}
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// PARSE PERCISION
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if (*format == '.')
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{
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format++;
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int percision = 0;
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if (isdigit(*format))
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{
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while (isdigit(*format))
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{
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percision *= 10;
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percision += *format - '0';
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format++;
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}
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}
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else if (*format == '*')
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{
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percision = va_arg(arguments, int);
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}
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options.percision = percision;
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}
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// TODO: Lenght modifier
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static char conversion[100];
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const char* string = nullptr;
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switch (*format)
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{
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case 'd':
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case 'i':
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{
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int value = va_arg(arguments, int);
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integer_to_string<int>(conversion, value, 10, false, options);
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string = conversion;
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format++;
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break;
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}
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case 'o':
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{
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unsigned int value = va_arg(arguments, unsigned int);
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integer_to_string<unsigned int>(conversion, value, 8, false, options);
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string = conversion;
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format++;
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break;
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}
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case 'u':
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{
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unsigned int value = va_arg(arguments, unsigned int);
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integer_to_string<unsigned int>(conversion, value, 10, false, options);
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string = conversion;
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format++;
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break;
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}
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case 'x':
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case 'X':
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{
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unsigned int value = va_arg(arguments, unsigned int);
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integer_to_string<unsigned int>(conversion, value, 16, *format == 'X', options);
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string = conversion;
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format++;
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break;
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}
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case 'e':
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case 'E':
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{
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double value = va_arg(arguments, double);
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floating_point_to_exponent_string<double>(conversion, value, *format == 'E', options);
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string = conversion;
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format++;
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break;
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}
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case 'f':
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case 'F':
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{
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double value = va_arg(arguments, double);
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floating_point_to_string<double>(conversion, value, *format == 'F', options);
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string = conversion;
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format++;
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break;
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}
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case 'g':
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case 'G':
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// TODO
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break;
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case 'a':
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case 'A':
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// TODO
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break;
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case 'c':
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{
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conversion[0] = va_arg(arguments, int);
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conversion[1] = '\0';
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string = conversion;
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format++;
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break;
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}
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case 's':
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{
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string = va_arg(arguments, const char*);
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format++;
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break;
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}
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case 'C':
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// TODO (depricated)
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break;
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case 'S':
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// TODO (depricated)
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break;
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case 'p':
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{
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void* ptr = va_arg(arguments, void*);
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options.alternate_form = true;
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integer_to_string<uintptr_t>(conversion, (uintptr_t)ptr, 16, false, options);
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string = conversion;
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format++;
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break;
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}
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case 'n':
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{
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int* target = va_arg(arguments, int*);
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*target = written;
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format++;
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break;
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}
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case 'm':
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{
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// NOTE: this is a glibc extension
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if (options.alternate_form)
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string = strerrorname_np(errno);
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else
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string = strerror(errno);
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format++;
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break;
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}
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case '%':
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{
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conversion[0] = '%';
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conversion[1] = '\0';
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string = conversion;
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format++;
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break;
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}
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default:
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break;
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}
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if (string)
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{
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int len = strlen(string);
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if (options.width == -1)
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options.width = 0;
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if (!options.left_justified)
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for (int i = len; i < options.width; i++)
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BAN_PRINTF_PUTC(' ');
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while (*string)
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{
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BAN_PRINTF_PUTC(*string);
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string++;
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}
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if (options.left_justified)
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for (int i = len; i < options.width; i++)
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BAN_PRINTF_PUTC(' ');
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}
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}
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else
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{
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BAN_PRINTF_PUTC(*format);
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format++;
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}
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}
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return written;
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}
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