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
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
}
}
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/*
#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
}
| 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 |
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