History

Bogdan Marinescu 75845c3dc7 Remove references to ssize_t in the code ssize_t doesn't exist at all in armcc.		2017-11-02 17:12:06 +00:00
..
TESTS/minimal-printf/compliance	Fixed bug in getting absolute value	2017-10-26 13:28:08 -07:00
profiles	Add "-g" to 'release' and 'develop' profiles	2017-10-30 19:10:19 +02:00
README.md	Add compile profiles	2017-10-27 14:44:31 +03:00
mbed_lib.json	Fix file permissions	2017-10-26 13:41:32 -07:00
mbed_printf.c	Add support for width specifiers	2017-10-26 07:28:15 -07:00
mbed_printf.h	Fix file permissions	2017-10-26 13:41:32 -07:00
mbed_printf_implementation.c	Remove references to ssize_t in the code	2017-11-02 17:12:06 +00:00
mbed_printf_implementation.h	Add test case	2017-10-26 08:56:00 -07:00
mbed_printf_wrapper.c	Add support for width specifiers	2017-10-26 07:28:15 -07:00

README.md

Minimal printf and snprintf

Library supports both printf and snprintf in 1252 bytes of flash.

Prints directly to stdio/UART without using malloc. All flags and precision modifiers are ignored. Floating point is disabled by default.

Supports:

%d: signed integer [h, hh, (none), l, ll, z, j, t].
%i: signed integer [h, hh, (none), l, ll, z, j, t].
%u: unsigned integer [h, hh, (none), l, ll, z, j, t].
%x: unsigned integer [h, hh, (none), l, ll, z, j, t], printed as hexadecimal number (e.g., FF).
%X: unsigned integer [h, hh, (none), l, ll, z, j, t], printed as hexadecimal number (e.g., FF).
%f: floating point (disabled by default).
%F: floating point (disabled by default).
%g: floating point (disabled by default).
%G: floating point (disabled by default).
%c: character.
%s: string.
%p: pointer (e.g. 0x00123456).

To replace the standard implementations of the printf functions with the ones in this library:

Add the library to your project.
Compile with mbed-cli using one of the custom profiles in the profiles/ subdirectory. For example, to compile in release mode:

$ mbed compile -t <toolchain> -m <target> --profile mbed-printf/profiles/release.json

Enabling floating point, 64 bit integers, new line conversion, and setting baud rate

In mbed_app.json:

    "target_overrides": {
        "*": {
            "platform.stdio-baud-rate": 115200,
            "platform.stdio-convert-newlines": false,
            "minimal-printf.enable-floating-point": false,
            "minimal-printf.set-floating-point-max-decimals": 6,
            "minimal-printf.enable-64-bit": true
        }
    }

Size comparison

Example application compiled with minimal mbed OS (no RTOS) using this .mbedignore:

mbed-os/rtos/*
mbed-os/features/FEATURE_LWIP/*
mbed-os/features/FEATURE_CLIENT/*
mbed-os/features/FEATURE_COMMON_PAL/*
mbed-os/features/FEATURE_UVISOR/*
mbed-os/features/frameworks/*
mbed-os/features/net/*
mbed-os/features/netsocket/*
mbed-os/features/storage/*
mbed-os/events/*

Example application

#include "mbed.h"
#include "mbed_printf.h"
#include <limits.h>

int main()
{
    char buffer[1000];
    int result;

    double pi = 3.14159265359;

#if 0
    result = printf("hello world %d %u %X %p %s %2.5f %% %\r\n", LONG_MAX, ULONG_MAX, UCHAR_MAX, buffer, "muh", pi);
    printf("results: %d\r\n", result);

    result = snprintf(buffer, 1000, "hello world %d %u %X %p %s %2.5f %% %\r\n", LONG_MIN, 0, 0, buffer, "muh", -1*pi);
    printf("%s\r\n", buffer);

    printf("results: %d\r\n", result);

#else
    result = mbed_printf("hello world %ld %llu %02X %p %s %2.5f %% %\r\n", LONG_MAX, ULONG_MAX, UCHAR_MAX, buffer, "muh", pi);
    mbed_printf("results: %d\r\n", result);

    result = mbed_snprintf(buffer, 1000, "hello world %d %u %X %p %s %2.5f %% %\r\n", LONG_MIN, 0, 0, buffer, "muh", -1*pi);
    mbed_printf("%s\r\n", buffer);

    mbed_printf("results: %d\r\n", result);
#endif
}

Full application size on K64F/GCC

	Floating point	64 bit integers	Flash	RAM
mbed-printf			7772	2752
mbed-printf		X	8708	2752
mbed-printf	X		10368	2752
mbed-printf	X	X	11360	2752
std printf	X	X	37354	5364