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LibC: add working f modifier to printf 

This is implementation will write out of bounds if the conversion
takes more than 1024 characters (either super large number or very
big percision).

Also we dont handle NaN and infinity cases
This commit is contained in:
Bananymous 2023-05-10 15:41:11 +03:00
parent f43bfcb398
commit 67005a80be
1 changed files with 53 additions and 5 deletions
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58
libc/printf_impl.cpp
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@ -1,3 +1,4 @@
#include <BAN/Traits.h>
#include <ctype.h> #include <ctype.h>
#include <errno.h> #include <errno.h>
#include <stdio.h> #include <stdio.h>
@ -22,7 +23,7 @@ struct format_options_t
int percision { -1 }; int percision { -1 };
}; };
template<typename T> template<BAN::integral T>
static void integer_to_string(char* buffer, T value, int base, bool upper, const format_options_t options) static void integer_to_string(char* buffer, T value, int base, bool upper, const format_options_t options)
{ {
int width = 1; int width = 1;
@ -94,7 +95,7 @@ static void integer_to_string(char* buffer, T value, int base, bool upper, const
buffer[offset++] = '\0'; buffer[offset++] = '\0';
} }
template<typename T> template<BAN::floating_point T>
static void floating_point_to_exponent_string(char* buffer, T value, bool upper, const format_options_t options) static void floating_point_to_exponent_string(char* buffer, T value, bool upper, const format_options_t options)
{ {
int percision = 6; int percision = 6;
@ -104,14 +105,59 @@ static void floating_point_to_exponent_string(char* buffer, T value, bool upper,
strcpy(buffer, "??e??"); strcpy(buffer, "??e??");
} }
template<typename T> template<BAN::floating_point T>
static void floating_point_to_string(char* buffer, T value, bool upper, const format_options_t options) static void floating_point_to_string(char* buffer, T value, bool upper, const format_options_t options)
{ {
int percision = 6; int percision = 6;
if (options.percision != -1) if (options.percision != -1)
percision = options.percision; percision = options.percision;
strcpy(buffer, "??.??"); int offset = 0;
if (value < 0)
{
buffer[offset++] = '-';
value = -value;
}
else if (options.show_plus_sign)
buffer[offset++] = '+';
else if (options.show_plus_sign_as_space)
buffer[offset++] = ' ';
int exponent = 1;
while (value > exponent * 10)
exponent *= 10;
T fractional = value;
while (exponent >= 1)
{
int scale = 0;
for (; scale < 10; scale++)
if (fractional < T(exponent * (scale + 1)))
break;
buffer[offset++] = '0' + scale;
fractional -= T(exponent * scale);
exponent /= 10;
}
if (!options.alternate_form && percision <= 0)
{
buffer[offset++] = '\0';
return;
}
buffer[offset++] = '.';
for (int i = 0; i < percision; i++)
{
fractional *= T(10.0);
if (i == percision - 1)
fractional += T(0.5);
int digit = fractional;
buffer[offset++] = '0' + digit;
fractional -= T(digit);
}
buffer[offset++] = '\0';
} }
extern "C" int printf_impl(const char* format, va_list arguments, int (*putc_fun)(int, void*), void* data) extern "C" int printf_impl(const char* format, va_list arguments, int (*putc_fun)(int, void*), void* data)
@ -179,12 +225,14 @@ extern "C" int printf_impl(const char* format, va_list arguments, int (*putc_fun
{ {
percision = va_arg(arguments, int); percision = va_arg(arguments, int);
} }
if (percision < 0)
percision = -1;
options.percision = percision; options.percision = percision;
} }
// TODO: Lenght modifier // TODO: Lenght modifier
static char conversion[100]; static char conversion[1024];
const char* string = nullptr; const char* string = nullptr;
switch (*format) switch (*format)