A tiny printf for embedded applications - by Kustaa Nyholm
Dependents: lpc1768-picotcp-demo
Diff: printf.h
- Revision:
- 0:aa3b196cf64f
diff -r 000000000000 -r aa3b196cf64f printf.h --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/printf.h Fri May 17 12:49:09 2013 +0000 @@ -0,0 +1,107 @@ +/* +File: printf.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 realy just two files: 'printf.h' and 'printf.c'. + +They provide a simple and small (+200 loc) printf functionality to +be used in embedded systems. + +I've found them so usefull 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 sprintf. + +The formats supported by this implementation are: 'd' 'u' 'c' '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 noticably longer. + +The memory foot print of course depends on the target cpu, compiler and +compiler options, but a rough guestimate (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 milage may vary. By hacking the source code you can +get rid of some hunred 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 realy) 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 interupts 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'. This makes it possible +to use them along with 'stdio.h' printf's in a single source file. +You just need to undef the names before you include the 'stdio.h'. +Note that these 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 +fucnction. If it is a problem just give up the macros and use the +functions directly or rename them. + +For further details see source code. + +regs Kusti, 23.10.2004 +*/ + +#ifndef __TFP_PRINTF__ +#define __TFP_PRINTF__ + +#include <stdarg.h> + +void init_printf(void *putp, void (*putf) (void *, char)); + +void tfp_printf(char *fmt, ...); +void tfp_sprintf(char *s, char *fmt, ...); + +void tfp_format(void *putp, void (*putf) (void *, char), char *fmt, va_list va); + +#define mprintf tfp_printf +#define msprintf tfp_sprintf + +#define PRINTF_LONG_SUPPORT + +#endif \ No newline at end of file