/* ----------------------------------------------------------------------------
 *         ATMEL Microcontroller Software Support 
 * ----------------------------------------------------------------------------
 * Copyright (c) 2008, Atmel Corporation
 * Copyright (c) 2018, sysmocom -s.f.m.c. GmbH, Author: Kevin Redon <kredon@sysmocom.de>
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the disclaimer below.
 *
 * Atmel's name may not be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * DISCLAIMER: THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
 * DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
 * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * ----------------------------------------------------------------------------
 */

//------------------------------------------------------------------------------
/// \unit
///
/// !Purpose
///
/// Implementation of several stdio.h methods, such as printf(), sprintf() and
/// so on. This reduces the memory footprint of the binary when using those
/// methods, compared to the libc implementation.
///
/// !Usage
///
/// Adds stdio.c to the list of file to compile for the project. This will
/// automatically replace libc methods by the custom ones.
//------------------------------------------------------------------------------

//------------------------------------------------------------------------------
//         Headers
//------------------------------------------------------------------------------

#include <stdio.h>
#include <stdarg.h>

//------------------------------------------------------------------------------
//         Local Definitions
//------------------------------------------------------------------------------

// Maximum string size allowed (in bytes).
#define MAX_STRING_SIZE         512

//------------------------------------------------------------------------------
//         Global Variables
//------------------------------------------------------------------------------
//
FILE* const stdin = NULL;
/* If we use NULL here, we get compiler warnings of calling stdio functions with
 * NULL values.  Our fputs() implementation ignores the value of those pointers anyway */
FILE* const stdout = (FILE *) 0x1;
FILE* const stderr = (FILE *) 0x2;


//------------------------------------------------------------------------------
//         Local Functions
//------------------------------------------------------------------------------

//------------------------------------------------------------------------------
// Writes a character inside the given string. Returns 1.
// \param pStr  Storage string.
// \param c  Character to write.
//------------------------------------------------------------------------------
signed int PutChar(char *pStr, char c)
{
	*pStr = c;
	return 1;
}

//------------------------------------------------------------------------------
// Writes a string inside the given string.
// Returns the size of the written
// string.
// \param pStr  Storage string.
// \param pSource  Source string.
//------------------------------------------------------------------------------
signed int PutString(char *pStr, const char *pSource)
{
	signed int num = 0;

	while (*pSource != 0) {

		*pStr++ = *pSource++;
		num++;
	}

	return num;
}

//------------------------------------------------------------------------------
// Writes an unsigned int inside the given string, using the provided fill &
// width parameters.
// Returns the size in characters of the written integer.
// \param pStr  Storage string.
// \param fill  Fill character.
// \param width  Minimum integer width.
// \param value  Integer value.
//------------------------------------------------------------------------------
signed int PutUnsignedInt(
	char *pStr,
	char fill,
	signed int width,
	unsigned int value)
{
	signed int num = 0;

	// Take current digit into account when calculating width
	width--;

	// Recursively write upper digits
	if ((value / 10) > 0) {

		num = PutUnsignedInt(pStr, fill, width, value / 10);
		pStr += num;
	}
	// Write filler characters
	else {

		while (width > 0) {

			PutChar(pStr, fill);
			pStr++;
			num++;
			width--;
		}
	}

	// Write lower digit
	num += PutChar(pStr, (value % 10) + '0');

	return num;
}

//------------------------------------------------------------------------------
// Writes a signed int inside the given string, using the provided fill & width
// parameters.
// Returns the size of the written integer.
// \param pStr  Storage string.
// \param fill  Fill character.
// \param width  Minimum integer width.
// \param value  Signed integer value.
//------------------------------------------------------------------------------
signed int PutSignedInt(
	char *pStr,
	char fill,
	signed int width,
	signed int value)
{
	signed int num = 0;
	unsigned int absolute;

	// Compute absolute value
	if (value < 0) {

		absolute = -value;
	}
	else {

		absolute = value;
	}

	// Take current digit into account when calculating width
	width--;

	// Recursively write upper digits
	if ((absolute / 10) > 0) {

		if (value < 0) {
		
			num = PutSignedInt(pStr, fill, width, -(absolute / 10));
		}
		else {

			num = PutSignedInt(pStr, fill, width, absolute / 10);
		}
		pStr += num;
	}
	else {

		// Reserve space for sign
		if (value < 0) {

			width--;
		}

		// Write filler characters
		while (width > 0) {

			PutChar(pStr, fill);
			pStr++;
			num++;
			width--;
		}

		// Write sign
		if (value < 0) {

			num += PutChar(pStr, '-');
			pStr++;
		}
	}

	// Write lower digit
	num += PutChar(pStr, (absolute % 10) + '0');

	return num;
}

//------------------------------------------------------------------------------
// Writes an hexadecimal value into a string, using the given fill, width &
// capital parameters.
// Returns the number of char written.
// \param pStr  Storage string.
// \param fill  Fill character.
// \param width  Minimum integer width.
// \param maj  Indicates if the letters must be printed in lower- or upper-case.
// \param value  Hexadecimal value.
//------------------------------------------------------------------------------
signed int PutHexa(
	char *pStr,
	char fill,
	signed int width,
	unsigned char maj,
	unsigned int value)
{
	signed int num = 0;

	// Decrement width
	width--;

	// Recursively output upper digits
	if ((value >> 4) > 0) {

		num += PutHexa(pStr, fill, width, maj, value >> 4);
		pStr += num;
	}
	// Write filler chars
	else {

		while (width > 0) {

			PutChar(pStr, fill);
			pStr++;
			num++;
			width--;
		}
	}

	// Write current digit
	if ((value & 0xF) < 10) {

		PutChar(pStr, (value & 0xF) + '0');
	}
	else if (maj) {

		PutChar(pStr, (value & 0xF) - 10 + 'A');
	}
	else {

		PutChar(pStr, (value & 0xF) - 10 + 'a');
	}
	num++;

	return num;
}

//------------------------------------------------------------------------------
//         Global Functions
//------------------------------------------------------------------------------

//------------------------------------------------------------------------------
/// Stores the result of a formatted string into another string. Format
/// arguments are given in a va_list instance.
/// Return the number of characters written.
/// \param pStr    Destination string.
/// \param length  Length of Destination string.
/// \param pFormat Format string.
/// \param ap      Argument list.
//------------------------------------------------------------------------------
signed int vsnprintf(char *pStr, size_t length, const char *pFormat, va_list ap)
{
	char          fill;
	unsigned char width;
	signed int    num = 0;
	size_t        size = 0;

	// Clear the string
	if (pStr) {

		*pStr = 0;
	}

	// Phase string
	while (*pFormat != 0 && size < length) {

		// Normal character
		if (*pFormat != '%') {

			*pStr++ = *pFormat++;
			size++;
		}
		// Escaped '%'
		else if (*(pFormat+1) == '%') {

			*pStr++ = '%';
			pFormat += 2;
			size++;
		}
		// Token delimiter
		else {

			fill = ' ';
			width = 0;
			pFormat++;

			// Parse filler
			if (*pFormat == '0') {

				fill = '0';
				pFormat++;
			}

			// Parse width
			while ((*pFormat >= '0') && (*pFormat <= '9')) {
		
				width = (width*10) + *pFormat-'0';
				pFormat++;
			}

			// Check if there is enough space
			if (size + width > length) {

				width = length - size;
			}
		
			// Parse type
			switch (*pFormat) {
			case 'd': 
			case 'i': num = PutSignedInt(pStr, fill, width, va_arg(ap, signed int)); break;
			case 'u': num = PutUnsignedInt(pStr, fill, width, va_arg(ap, unsigned int)); break;
			case 'x': num = PutHexa(pStr, fill, width, 0, va_arg(ap, unsigned int)); break;
			case 'X': num = PutHexa(pStr, fill, width, 1, va_arg(ap, unsigned int)); break;
			case 's': num = PutString(pStr, va_arg(ap, char *)); break;
			case 'c': num = PutChar(pStr, va_arg(ap, unsigned int)); break;
			default:
				return EOF;
			}

			pFormat++;
			pStr += num;
			size += num;
		}
	}

	// NULL-terminated (final \0 is not counted)
	if (size < length) {

		*pStr = 0;
	}
	else {

		*(--pStr) = 0;
		size--;
	}

	return size;
}

//------------------------------------------------------------------------------
/// Stores the result of a formatted string into another string. Format
/// arguments are given in a va_list instance.
/// Return the number of characters written.
/// \param pString Destination string.
/// \param length  Length of Destination string.
/// \param pFormat Format string.
/// \param ...     Other arguments
//------------------------------------------------------------------------------
signed int snprintf(char *pString, size_t length, const char *pFormat, ...)
{
	va_list    ap;
	signed int rc;

	va_start(ap, pFormat);
	rc = vsnprintf(pString, length, pFormat, ap);
	va_end(ap);

	return rc;
}

//------------------------------------------------------------------------------
/// Stores the result of a formatted string into another string. Format
/// arguments are given in a va_list instance.
/// Return the number of characters written.
/// \param pString  Destination string.
/// \param pFormat  Format string.
/// \param ap       Argument list.
//------------------------------------------------------------------------------
signed int vsprintf(char *pString, const char *pFormat, va_list ap)
{
	return vsnprintf(pString, MAX_STRING_SIZE, pFormat, ap);
}

//------------------------------------------------------------------------------
/// Outputs a formatted string on the given stream. Format arguments are given
/// in a va_list instance.
/// \param pStream  Output stream.
/// \param pFormat  Format string
/// \param ap  Argument list.
//------------------------------------------------------------------------------
signed int vfprintf(FILE *pStream, const char *pFormat, va_list ap)
{
	char pStr[MAX_STRING_SIZE];
	char pError[] = "stdio.c: increase MAX_STRING_SIZE\n\r";

	// Write formatted string in buffer
	if (vsprintf(pStr, pFormat, ap) >= MAX_STRING_SIZE) {

		fputs(pError, stderr);
	}

	// Display string
	return fputs(pStr, pStream);
}

//------------------------------------------------------------------------------
/// Outputs a formatted string on the given stream. Format arguments are given
/// in a va_list instance.
/// \note This function is synchronous (i.e. blocks until the print completes)
/// \param pStream  Output stream.
/// \param pFormat  Format string
/// \param ap  Argument list.
//------------------------------------------------------------------------------
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wsuggest-attribute=format"
signed int vfprintf_sync(FILE *pStream, const char *pFormat, va_list ap)
{
	char pStr[MAX_STRING_SIZE];
	char pError[] = "stdio.c: increase MAX_STRING_SIZE\n\r";

	// Write formatted string in buffer
	if (vsprintf(pStr, pFormat, ap) >= MAX_STRING_SIZE) {

		fputs_sync(pError, stderr);
	}

	// Display string
	return fputs_sync(pStr, pStream);
}
#pragma GCC diagnostic pop

//------------------------------------------------------------------------------
/// Outputs a formatted string on the DBGU stream. Format arguments are given
/// in a va_list instance.
/// \param pFormat  Format string
/// \param ap  Argument list.
//------------------------------------------------------------------------------
signed int vprintf(const char *pFormat, va_list ap)
{
	return vfprintf(stdout, pFormat, ap);
}

//------------------------------------------------------------------------------
/// Outputs a formatted string on the DBGU stream. Format arguments are given
/// in a va_list instance.
/// \note This function is synchronous (i.e. blocks until the print completes)
/// \param pFormat  Format string
/// \param ap  Argument list.
//------------------------------------------------------------------------------
signed int vprintf_sync(const char *pFormat, va_list ap)
{
	return vfprintf_sync(stdout, pFormat, ap);
}

//------------------------------------------------------------------------------
/// Outputs a formatted string on the given stream, using a variable number of
/// arguments.
/// \param pStream  Output stream.
/// \param pFormat  Format string.
//------------------------------------------------------------------------------
signed int fprintf(FILE *pStream, const char *pFormat, ...)
{
	va_list ap;
	signed int result;

	// Forward call to vfprintf
	va_start(ap, pFormat);
	result = vfprintf(pStream, pFormat, ap);
	va_end(ap);

	return result;
}

//------------------------------------------------------------------------------
/// Outputs a formatted string on the DBGU stream, using a variable number of
/// arguments.
/// \param pFormat  Format string.
//------------------------------------------------------------------------------
signed int printf(const char *pFormat, ...)
{
	va_list ap;
	signed int result;

	// Forward call to vprintf
	va_start(ap, pFormat);
	result = vprintf(pFormat, ap);
	va_end(ap);

	return result;
}

//------------------------------------------------------------------------------
/// Outputs a formatted string on the DBGU stream, using a variable number of
/// arguments.
/// \note This function is synchronous (i.e. blocks until the print completes)
/// \param pFormat  Format string.
//------------------------------------------------------------------------------
signed int printf_sync(const char *pFormat, ...)
{
	va_list ap;
	signed int result;

	// Forward call to vprintf
	va_start(ap, pFormat);
	result = vprintf_sync(pFormat, ap);
	va_end(ap);

	return result;
}

//------------------------------------------------------------------------------
/// Writes a formatted string inside another string.
/// \param pStr  Storage string.
/// \param pFormat  Format string.
//------------------------------------------------------------------------------
signed int sprintf(char *pStr, const char *pFormat, ...)
{
	va_list ap;
	signed int result;

	// Forward call to vsprintf
	va_start(ap, pFormat);
	result = vsprintf(pStr, pFormat, ap);
	va_end(ap);

	return result;
}

//------------------------------------------------------------------------------
/// Outputs a string on stdout.
/// \param pStr  String to output.
//------------------------------------------------------------------------------
signed int puts(const char *pStr)
{
	return fputs(pStr, stdout);
}