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tinyprintf.h
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tinyprintf.h
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/*
File: tinyprintf.h
Copyright (C) 2004 Kustaa Nyholm
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
This library is really just two files: 'tinyprintf.h' and 'tinyprintf.c'.
They provide a simple and small (+400 loc) printf functionality to
be used in embedded systems.
I've found them so useful in debugging that I do not bother with a
debugger at all.
They are distributed in source form, so to use them, just compile them
into your project.
Two printf variants are provided: printf and the 'sprintf' family of
functions ('snprintf', 'sprintf', 'vsnprintf', 'vsprintf').
The formats supported by this implementation are:
'c' 'd' 'i' 'o' 'p' 'u' 's' 'x' 'X'.
Zero padding and field width are also supported.
If the library is compiled with 'PRINTF_SUPPORT_LONG' defined, then
the long specifier is also supported. Note that this will pull in some
long math routines (pun intended!) and thus make your executable
noticeably longer. Likewise with 'PRINTF_LONG_LONG_SUPPORT' for the
long long specifier, and with 'PRINTF_SIZE_T_SUPPORT' for the size_t
specifier.
The memory footprint of course depends on the target CPU, compiler and
compiler options, but a rough guesstimate (based on a H8S target) is about
1.4 kB for code and some twenty 'int's and 'char's, say 60 bytes of stack space.
Not too bad. Your mileage may vary. By hacking the source code you can
get rid of some hundred bytes, I'm sure, but personally I feel the balance of
functionality and flexibility versus code size is close to optimal for
many embedded systems.
To use the printf, you need to supply your own character output function,
something like :
void putc ( void* p, char c)
{
while (!SERIAL_PORT_EMPTY) ;
SERIAL_PORT_TX_REGISTER = c;
}
Before you can call printf, you need to initialize it to use your
character output function with something like:
init_printf(NULL,putc);
Notice the 'NULL' in 'init_printf' and the parameter 'void* p' in 'putc',
the NULL (or any pointer) you pass into the 'init_printf' will eventually be
passed to your 'putc' routine. This allows you to pass some storage space (or
anything really) to the character output function, if necessary.
This is not often needed but it was implemented like that because it made
implementing the sprintf function so neat (look at the source code).
The code is re-entrant, except for the 'init_printf' function, so it is safe
to call it from interrupts too, although this may result in mixed output.
If you rely on re-entrancy, take care that your 'putc' function is re-entrant!
The printf and sprintf functions are actually macros that translate to
'tfp_printf' and 'tfp_sprintf' when 'TINYPRINTF_OVERRIDE_LIBC' is set
(default). Setting it to 0 makes it possible to use them along with
'stdio.h' printf's in a single source file. When
'TINYPRINTF_OVERRIDE_LIBC' is set, please note that printf/sprintf are
not function-like macros, so if you have variables or struct members
with these names, things will explode in your face. Without variadic
macros this is the best we can do to wrap these function. If it is a
problem, just give up the macros and use the functions directly, or
rename them.
It is also possible to avoid defining tfp_printf and/or tfp_sprintf by
clearing 'TINYPRINTF_DEFINE_TFP_PRINTF' and/or
'TINYPRINTF_DEFINE_TFP_SPRINTF' to 0. This allows for example to
export only tfp_format, which is at the core of all the other
functions.
For further details see source code.
regs Kusti, 23.10.2004
*/
#ifndef __TFP_PRINTF__
#define __TFP_PRINTF__
#include <stdarg.h>
/* Global configuration */
/* Set this to 0 if you do not want to provide tfp_printf */
#ifndef TINYPRINTF_DEFINE_TFP_PRINTF
# define TINYPRINTF_DEFINE_TFP_PRINTF 1
#endif
/* Set this to 0 if you do not want to provide
tfp_sprintf/snprintf/vsprintf/vsnprintf */
#ifndef TINYPRINTF_DEFINE_TFP_SPRINTF
# define TINYPRINTF_DEFINE_TFP_SPRINTF 1
#endif
/* Set this to 0 if you do not want tfp_printf and
tfp_{vsn,sn,vs,s}printf to be also available as
printf/{vsn,sn,vs,s}printf */
#ifndef TINYPRINTF_OVERRIDE_LIBC
# define TINYPRINTF_OVERRIDE_LIBC 1
#endif
/* Optional external types dependencies */
#if TINYPRINTF_DEFINE_TFP_SPRINTF
# include <sys/types.h> /* size_t */
#endif
/* Declarations */
#ifdef __GNUC__
# define _TFP_SPECIFY_PRINTF_FMT(fmt_idx,arg1_idx) \
__attribute__((format (printf, fmt_idx, arg1_idx)))
#else
# define _TFP_SPECIFY_PRINTF_FMT(fmt_idx,arg1_idx)
#endif
#ifdef __cplusplus
extern "C" {
#endif
typedef void (*putcf) (void *, char);
/*
'tfp_format' really is the central function for all tinyprintf. For
each output character after formatting, the 'putf' callback is
called with 2 args:
- an arbitrary void* 'putp' param defined by the user and
passed unmodified from 'tfp_format',
- the character.
The 'tfp_printf' and 'tfp_sprintf' functions simply define their own
callback and pass to it the right 'putp' it is expecting.
*/
void tfp_format(void *putp, putcf putf, const char *fmt, va_list va);
#if TINYPRINTF_DEFINE_TFP_SPRINTF
int tfp_vsnprintf(char *str, size_t size, const char *fmt, va_list ap);
int tfp_snprintf(char *str, size_t size, const char *fmt, ...) \
_TFP_SPECIFY_PRINTF_FMT(3, 4);
int tfp_vsprintf(char *str, const char *fmt, va_list ap);
int tfp_sprintf(char *str, const char *fmt, ...) \
_TFP_SPECIFY_PRINTF_FMT(2, 3);
# if TINYPRINTF_OVERRIDE_LIBC
# define vsnprintf tfp_vsnprintf
# define snprintf tfp_snprintf
# define vsprintf tfp_vsprintf
# define sprintf tfp_sprintf
# endif
#endif
#if TINYPRINTF_DEFINE_TFP_PRINTF
void init_printf(void *putp, putcf putf);
void tfp_printf(char *fmt, ...) _TFP_SPECIFY_PRINTF_FMT(1, 2);
# if TINYPRINTF_OVERRIDE_LIBC
# define printf tfp_printf
# endif
#endif
#ifdef __cplusplus
}
#endif
#endif