strcpy(), strcpy

Copy a string

Synopsis:

#include <string.h>

char* strcpy( char* dst, 
              const char* src );

char* strcpy_isr( char* dst, 
                  const char* src );

Arguments:

dst: A pointer to where you want to copy the string.
src: The string that you want to copy.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The strcpy() function copies the string pointed to by src (including the terminating NUL character) into the array pointed to by dst. The strcpy_isr() function is similar, but it's safe for you to use it in an interrupt service routine.

Note: Copying of overlapping objects isn't guaranteed to work properly. See the memmove() function for information on copying objects that overlap.

Returns:

The same pointer as dst.

Examples:

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int main( void )
{
    char buffer[80];

    strcpy( buffer, "Hello " );
    strcat( buffer, "world" );

    printf( "%s\n", buffer );

    return EXIT_SUCCESS;
}

produces the output:

Hello world

Environment variables:

LIBC_STRINGS

On certain targets, you can use this environment variable to select the implementation of strcpy(). It doesn't affect the implementation of strcpy_isr(). The value is one of the strings given below.

for AArch64 targets:
- aarch64_neon — optimized for AARCH64 targets using NEON
- generic — the default
for ARMv7 targets:
- cortex_a9 — optimized for the ARM Cortex-A9 processor; assumes that no unaligned access is supported
- cortex_a9_aligned — optimized for ARM Cortex-A9; requires that unaligned memory access be enabled on the platform. If memory access is misaligned, this implementation falls back to the NEON version.
- cortex_a9_neon — optimized for ARM Cortex-A9 using NEON
- generic — the default
- krait — optimized for the Qualcomm Krait CPU
- krait_neon — optimized for Qualcomm Krait using NEON

Processes that register ISRs shouldn't use the NEON versions.

Classification:

strcpy() is ANSI, POSIX 1003.1; strcpy_isr() is QNX Neutrino.

Table 1. strcpy()
Safety:
Cancellation point	No
Interrupt handler	Read the Caveats
Signal handler	Yes
Thread	Yes

Table 2. strcpy_isr()
Safety:
Cancellation point	No
Interrupt handler	Yes
Signal handler	Yes
Thread	Yes

Caveats:

Implementations of strcpy() that are optimized using SIMD instructions aren't safe to use in an interrupt handler. These include the NEON implementations on ARMv7 and AArch64.

strcpy(), strcpy_isr()