History

Bogdan Marinescu 362dd3fbcf Bugfixes for the implementation and the compliance test In the implementation, don't always display double hex digits when printing with "%X". This is in line with the behaviour observed both in mbed OS's printf (Newlib) and Linux's printf (glibc). In the tests, always compare the baseline result with the result returned by the minimal printf implementation, instead of comparing with a constant value.		2018-04-26 00:05:52 +03:00
..
TESTS/minimal-printf/compliance	Bugfixes for the implementation and the compliance test	2018-04-26 00:05:52 +03:00
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	Bugfixes for the implementation and the compliance test	2018-04-26 00:05:52 +03:00
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