TASS Belgium / picotcp-demo-printf

A tiny printf for embedded applications - by Kustaa Nyholm

Dependents:   lpc1768-picotcp-demo

printf.h@0:aa3b196cf64f, 2013-05-17 (annotated)

Committer:
tass
Date:
Fri May 17 12:49:09 2013 +0000
Revision:
0:aa3b196cf64f
supporting printf library

Who changed what in which revision?

UserRevisionLine numberNew contents of line
tass 0:aa3b196cf64f 1 /*
tass 0:aa3b196cf64f 2 File: printf.h
tass 0:aa3b196cf64f 3
tass 0:aa3b196cf64f 4 Copyright (C) 2004 Kustaa Nyholm
tass 0:aa3b196cf64f 5
tass 0:aa3b196cf64f 6 This library is free software; you can redistribute it and/or
tass 0:aa3b196cf64f 7 modify it under the terms of the GNU Lesser General Public
tass 0:aa3b196cf64f 8 License as published by the Free Software Foundation; either
tass 0:aa3b196cf64f 9 version 2.1 of the License, or (at your option) any later version.
tass 0:aa3b196cf64f 10
tass 0:aa3b196cf64f 11 This library is distributed in the hope that it will be useful,
tass 0:aa3b196cf64f 12 but WITHOUT ANY WARRANTY; without even the implied warranty of
tass 0:aa3b196cf64f 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
tass 0:aa3b196cf64f 14 Lesser General Public License for more details.
tass 0:aa3b196cf64f 15
tass 0:aa3b196cf64f 16 You should have received a copy of the GNU Lesser General Public
tass 0:aa3b196cf64f 17 License along with this library; if not, write to the Free Software
tass 0:aa3b196cf64f 18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
tass 0:aa3b196cf64f 19
tass 0:aa3b196cf64f 20 This library is realy just two files: 'printf.h' and 'printf.c'.
tass 0:aa3b196cf64f 21
tass 0:aa3b196cf64f 22 They provide a simple and small (+200 loc) printf functionality to
tass 0:aa3b196cf64f 23 be used in embedded systems.
tass 0:aa3b196cf64f 24
tass 0:aa3b196cf64f 25 I've found them so usefull in debugging that I do not bother with a
tass 0:aa3b196cf64f 26 debugger at all.
tass 0:aa3b196cf64f 27
tass 0:aa3b196cf64f 28 They are distributed in source form, so to use them, just compile them
tass 0:aa3b196cf64f 29 into your project.
tass 0:aa3b196cf64f 30
tass 0:aa3b196cf64f 31 Two printf variants are provided: printf and sprintf.
tass 0:aa3b196cf64f 32
tass 0:aa3b196cf64f 33 The formats supported by this implementation are: 'd' 'u' 'c' 's' 'x' 'X'.
tass 0:aa3b196cf64f 34
tass 0:aa3b196cf64f 35 Zero padding and field width are also supported.
tass 0:aa3b196cf64f 36
tass 0:aa3b196cf64f 37 If the library is compiled with 'PRINTF_SUPPORT_LONG' defined then the
tass 0:aa3b196cf64f 38 long specifier is also
tass 0:aa3b196cf64f 39 supported. Note that this will pull in some long math routines (pun intended!)
tass 0:aa3b196cf64f 40 and thus make your executable noticably longer.
tass 0:aa3b196cf64f 41
tass 0:aa3b196cf64f 42 The memory foot print of course depends on the target cpu, compiler and
tass 0:aa3b196cf64f 43 compiler options, but a rough guestimate (based on a H8S target) is about
tass 0:aa3b196cf64f 44 1.4 kB for code and some twenty 'int's and 'char's, say 60 bytes of stack space.
tass 0:aa3b196cf64f 45 Not too bad. Your milage may vary. By hacking the source code you can
tass 0:aa3b196cf64f 46 get rid of some hunred bytes, I'm sure, but personally I feel the balance of
tass 0:aa3b196cf64f 47 functionality and flexibility versus code size is close to optimal for
tass 0:aa3b196cf64f 48 many embedded systems.
tass 0:aa3b196cf64f 49
tass 0:aa3b196cf64f 50 To use the printf you need to supply your own character output function,
tass 0:aa3b196cf64f 51 something like :
tass 0:aa3b196cf64f 52
tass 0:aa3b196cf64f 53 void putc ( void* p, char c)
tass 0:aa3b196cf64f 54 {
tass 0:aa3b196cf64f 55 while (!SERIAL_PORT_EMPTY) ;
tass 0:aa3b196cf64f 56 SERIAL_PORT_TX_REGISTER = c;
tass 0:aa3b196cf64f 57 }
tass 0:aa3b196cf64f 58
tass 0:aa3b196cf64f 59 Before you can call printf you need to initialize it to use your
tass 0:aa3b196cf64f 60 character output function with something like:
tass 0:aa3b196cf64f 61
tass 0:aa3b196cf64f 62 init_printf(NULL,putc);
tass 0:aa3b196cf64f 63
tass 0:aa3b196cf64f 64 Notice the 'NULL' in 'init_printf' and the parameter 'void* p' in 'putc',
tass 0:aa3b196cf64f 65 the NULL (or any pointer) you pass into the 'init_printf' will eventually be
tass 0:aa3b196cf64f 66 passed to your 'putc' routine. This allows you to pass some storage space (or
tass 0:aa3b196cf64f 67 anything realy) to the character output function, if necessary.
tass 0:aa3b196cf64f 68 This is not often needed but it was implemented like that because it made
tass 0:aa3b196cf64f 69 implementing the sprintf function so neat (look at the source code).
tass 0:aa3b196cf64f 70
tass 0:aa3b196cf64f 71 The code is re-entrant, except for the 'init_printf' function, so it
tass 0:aa3b196cf64f 72 is safe to call it from interupts too, although this may result in mixed output.
tass 0:aa3b196cf64f 73 If you rely on re-entrancy, take care that your 'putc' function is re-entrant!
tass 0:aa3b196cf64f 74
tass 0:aa3b196cf64f 75 The printf and sprintf functions are actually macros that translate to
tass 0:aa3b196cf64f 76 'tfp_printf' and 'tfp_sprintf'. This makes it possible
tass 0:aa3b196cf64f 77 to use them along with 'stdio.h' printf's in a single source file.
tass 0:aa3b196cf64f 78 You just need to undef the names before you include the 'stdio.h'.
tass 0:aa3b196cf64f 79 Note that these are not function like macros, so if you have variables
tass 0:aa3b196cf64f 80 or struct members with these names, things will explode in your face.
tass 0:aa3b196cf64f 81 Without variadic macros this is the best we can do to wrap these
tass 0:aa3b196cf64f 82 fucnction. If it is a problem just give up the macros and use the
tass 0:aa3b196cf64f 83 functions directly or rename them.
tass 0:aa3b196cf64f 84
tass 0:aa3b196cf64f 85 For further details see source code.
tass 0:aa3b196cf64f 86
tass 0:aa3b196cf64f 87 regs Kusti, 23.10.2004
tass 0:aa3b196cf64f 88 */
tass 0:aa3b196cf64f 89
tass 0:aa3b196cf64f 90 #ifndef __TFP_PRINTF__
tass 0:aa3b196cf64f 91 #define __TFP_PRINTF__
tass 0:aa3b196cf64f 92
tass 0:aa3b196cf64f 93 #include <stdarg.h>
tass 0:aa3b196cf64f 94
tass 0:aa3b196cf64f 95 void init_printf(void *putp, void (*putf) (void *, char));
tass 0:aa3b196cf64f 96
tass 0:aa3b196cf64f 97 void tfp_printf(char *fmt, ...);
tass 0:aa3b196cf64f 98 void tfp_sprintf(char *s, char *fmt, ...);
tass 0:aa3b196cf64f 99
tass 0:aa3b196cf64f 100 void tfp_format(void *putp, void (*putf) (void *, char), char *fmt, va_list va);
tass 0:aa3b196cf64f 101
tass 0:aa3b196cf64f 102 #define mprintf tfp_printf
tass 0:aa3b196cf64f 103 #define msprintf tfp_sprintf
tass 0:aa3b196cf64f 104
tass 0:aa3b196cf64f 105 #define PRINTF_LONG_SUPPORT
tass 0:aa3b196cf64f 106
tass 0:aa3b196cf64f 107 #endif