pgm_read_byte • man page

pgm_read_byte (3)

NAME

avr_pgmspace

SYNOPSIS

Macros

#define PROGMEM __ATTR_PROGMEM__

#define PGM_P const char *

#define PGM_VOID_P const void *

#define PSTR(s) ((const PROGMEM char *)(s))

#define pgm_read_byte_near(address_short) __LPM((uint16_t)(address_short))

#define pgm_read_word_near(address_short) __LPM_word((uint16_t)(address_short))

#define pgm_read_dword_near(address_short) __LPM_dword((uint16_t)(address_short))

#define pgm_read_float_near(address_short) __LPM_float((uint16_t)(address_short))

#define pgm_read_ptr_near(address_short) (void*)__LPM_word((uint16_t)(address_short))

#define pgm_read_byte_far(address_long) __ELPM((uint32_t)(address_long))

#define pgm_read_word_far(address_long) __ELPM_word((uint32_t)(address_long))

#define pgm_read_dword_far(address_long) __ELPM_dword((uint32_t)(address_long))

#define pgm_read_float_far(address_long) __ELPM_float((uint32_t)(address_long))

#define pgm_read_ptr_far(address_long) (void*)__ELPM_word((uint32_t)(address_long))

#define pgm_read_byte(address_short) pgm_read_byte_near(address_short)

#define pgm_read_word(address_short) pgm_read_word_near(address_short)

#define pgm_read_dword(address_short) pgm_read_dword_near(address_short)

#define pgm_read_float(address_short) pgm_read_float_near(address_short)

#define pgm_read_ptr(address_short) pgm_read_ptr_near(address_short)

#define pgm_get_far_address(var)

Typedefs

typedef void PROGMEM prog_void

typedef char PROGMEM prog_char

typedef unsigned char PROGMEM prog_uchar

typedef int8_t PROGMEM prog_int8_t

typedef uint8_t PROGMEM prog_uint8_t

typedef int16_t PROGMEM prog_int16_t

typedef uint16_t PROGMEM prog_uint16_t

typedef int32_t PROGMEM prog_int32_t

typedef uint32_t PROGMEM prog_uint32_t

typedef int64_t PROGMEM prog_int64_t

typedef uint64_t PROGMEM prog_uint64_t

Functions

const void * memchr_P (const void *, int __val, size_t __len)

int memcmp_P (const void *, const void *, size_t) __ATTR_PURE__

void * memccpy_P (void *, const void *, int __val, size_t)

void * memcpy_P (void *, const void *, size_t)

void * memmem_P (const void *, size_t, const void *, size_t) __ATTR_PURE__

const void * memrchr_P (const void *, int __val, size_t __len)

char * strcat_P (char *, const char *)

const char * strchr_P (const char *, int __val)

const char * strchrnul_P (const char *, int __val)

int strcmp_P (const char *, const char *) __ATTR_PURE__

char * strcpy_P (char *, const char *)

int strcasecmp_P (const char *, const char *) __ATTR_PURE__

char * strcasestr_P (const char *, const char *) __ATTR_PURE__

size_t strcspn_P (const char *__s, const char *__reject) __ATTR_PURE__

size_t strlcat_P (char *, const char *, size_t)

size_t strlcpy_P (char *, const char *, size_t)

size_t strnlen_P (const char *, size_t)

int strncmp_P (const char *, const char *, size_t) __ATTR_PURE__

int strncasecmp_P (const char *, const char *, size_t) __ATTR_PURE__

char * strncat_P (char *, const char *, size_t)

char * strncpy_P (char *, const char *, size_t)

char * strpbrk_P (const char *__s, const char *__accept) __ATTR_PURE__

const char * strrchr_P (const char *, int __val)

char * strsep_P (char **__sp, const char *__delim)

size_t strspn_P (const char *__s, const char *__accept) __ATTR_PURE__

char * strstr_P (const char *, const char *) __ATTR_PURE__

char * strtok_P (char *__s, const char *__delim)

char * strtok_rP (char *__s, const char *__delim, char **__last)

size_t strlen_PF (uint_farptr_t src)

size_t strnlen_PF (uint_farptr_t src, size_t len)

void * memcpy_PF (void *dest, uint_farptr_t src, size_t len)

char * strcpy_PF (char *dest, uint_farptr_t src)

char * strncpy_PF (char *dest, uint_farptr_t src, size_t len)

char * strcat_PF (char *dest, uint_farptr_t src)

size_t strlcat_PF (char *dst, uint_farptr_t src, size_t siz)

char * strncat_PF (char *dest, uint_farptr_t src, size_t len)

int strcmp_PF (const char *s1, uint_farptr_t s2) __ATTR_PURE__

int strncmp_PF (const char *s1, uint_farptr_t s2, size_t n) __ATTR_PURE__

int strcasecmp_PF (const char *s1, uint_farptr_t s2) __ATTR_PURE__

int strncasecmp_PF (const char *s1, uint_farptr_t s2, size_t n) __ATTR_PURE__

char * strstr_PF (const char *s1, uint_farptr_t s2)

size_t strlcpy_PF (char *dst, uint_farptr_t src, size_t siz)

int memcmp_PF (const void *, uint_farptr_t, size_t) __ATTR_PURE__

static size_t strlen_P (const char *s)

Detailed Description

#include <avr/io.h>
#include <avr/pgmspace.h>

The functions in this module provide interfaces for a program to access data stored in program space (flash memory) of the device. In order to use these functions, the target device must support either the LPM or ELPM instructions.

Note:

These functions are an attempt to provide some compatibility with header files that come with IAR C, to make porting applications between different compilers easier. This is not 100% compatibility though (GCC does not have full support for multiple address spaces yet).

If you are working with strings which are completely based in ram, use the standard string functions described in <string.h>: Strings.

If possible, put your constant tables in the lower 64 KB and use pgm_read_byte_near() or pgm_read_word_near() instead of pgm_read_byte_far() or pgm_read_word_far() since it is more efficient that way, and you can still use the upper 64K for executable code. All functions that are suffixed with a _P require their arguments to be in the lower 64 KB of the flash ROM, as they do not use ELPM instructions. This is normally not a big concern as the linker setup arranges any program space constants declared using the macros from this header file so they are placed right after the interrupt vectors, and in front of any executable code. However, it can become a problem if there are too many of these constants, or for bootloaders on devices with more than 64 KB of ROM. All these functions will not work in that situation.

For Xmega devices, make sure the NVM controller command register (NVM.CMD or NVM_CMD) is set to 0x00 (NOP) before using any of these functions.

Macro Definition Documentation

#define pgm_get_far_address(var)

Value:

({                                                        uint_farptr_t tmp;                                                                                          __asm__ __volatile__(                                                                                               "ldi    %A0, lo8(%1)"           "t"                "ldi    %B0, hi8(%1)"           "t"                "ldi    %C0, hh8(%1)"           "t"                "clr    %D0"                    "t"            :                                                         "=d" (tmp)                                        :                                                         "p"  (&(var))                                 );                                                    tmp;                                              })

This macro facilitates the obtention of a 32 bit 'far' pointer (only 24 bits used) to data even passed the 64KB limit for the 16 bit ordinary pointer. It is similar to the '&' operator, with some limitations.

Comments:

*: The overhead is minimal and it's mainly due to the 32 bit size operation.
*: 24 bit sizes guarantees the code compatibility for use in future devices.
*: hh8() is an undocumented feature but seems to give the third significant byte of a 32 bit data and accepts symbols, complementing the functionality of hi8() and lo8(). There is not an equivalent assembler function to get the high significant byte.
*
*: The returned value is the identifier's VMA (virtual memory address) determined by the linker and falls in the corresponding memory region. The AVR Harvard architecture requires non overlapping VMA areas for the multiple address spaces in the processor: Flash ROM, RAM, and EEPROM. Typical offset for this are 0x00000000, 0x00800xx0, and 0x00810000 respectively, derived from the linker script used and linker options. The value returned can be seen then as a universal pointer.

#define PGM_P const char *

Used to declare a variable that is a pointer to a string in program space.

#define pgm_read_byte(address_short) pgm_read_byte_near(address_short)

Read a byte from the program space with a 16-bit (near) address.

Note:

: The address is a byte address. The address is in the program space.

#define pgm_read_byte_far(address_long) __ELPM((uint32_t)(address_long))

Read a byte from the program space with a 32-bit (far) address.

Note:

: The address is a byte address. The address is in the program space.

#define pgm_read_byte_near(address_short) __LPM((uint16_t)(address_short))

Read a byte from the program space with a 16-bit (near) address.

Note:

: The address is a byte address. The address is in the program space.

#define pgm_read_dword(address_short) pgm_read_dword_near(address_short)

Read a double word from the program space with a 16-bit (near) address.

Note:

: The address is a byte address. The address is in the program space.

#define pgm_read_dword_far(address_long) __ELPM_dword((uint32_t)(address_long))

Read a double word from the program space with a 32-bit (far) address.

Note:

: The address is a byte address. The address is in the program space.

#define pgm_read_dword_near(address_short) __LPM_dword((uint16_t)(address_short))

Read a double word from the program space with a 16-bit (near) address.

Note:

: The address is a byte address. The address is in the program space.

#define pgm_read_float(address_short) pgm_read_float_near(address_short)

Read a float from the program space with a 16-bit (near) address.

Note:

: The address is a byte address. The address is in the program space.

#define pgm_read_float_far(address_long) __ELPM_float((uint32_t)(address_long))

Read a float from the program space with a 32-bit (far) address.

Note:

: The address is a byte address. The address is in the program space.

#define pgm_read_float_near(address_short) __LPM_float((uint16_t)(address_short))

Read a float from the program space with a 16-bit (near) address.

Note:

: The address is a byte address. The address is in the program space.

#define pgm_read_ptr(address_short) pgm_read_ptr_near(address_short)

Read a pointer from the program space with a 16-bit (near) address.

Note:

: The address is a byte address. The address is in the program space.

#define pgm_read_ptr_far(address_long) (void*)__ELPM_word((uint32_t)(address_long))

Read a pointer from the program space with a 32-bit (far) address.

Note:

: The address is a byte address. The address is in the program space.

#define pgm_read_ptr_near(address_short) (void*)__LPM_word((uint16_t)(address_short))

Read a pointer from the program space with a 16-bit (near) address.

Note:

: The address is a byte address. The address is in the program space.

#define pgm_read_word(address_short) pgm_read_word_near(address_short)

Read a word from the program space with a 16-bit (near) address.

Note:

: The address is a byte address. The address is in the program space.

#define pgm_read_word_far(address_long) __ELPM_word((uint32_t)(address_long))

Read a word from the program space with a 32-bit (far) address.

Note:

: The address is a byte address. The address is in the program space.

#define pgm_read_word_near(address_short) __LPM_word((uint16_t)(address_short))

Read a word from the program space with a 16-bit (near) address.

Note:

: The address is a byte address. The address is in the program space.

#define PGM_VOID_P const void *

Used to declare a generic pointer to an object in program space.

#define PROGMEM __ATTR_PROGMEM__

Attribute to use in order to declare an object being located in flash ROM.

#define PSTR(s) ((const PROGMEM char *)(s))

Used to declare a static pointer to a string in program space.

Typedef Documentation

prog_char

Note:

: DEPRECATED

This typedef is now deprecated because the usage of the __progmem__ attribute on a type is not supported in GCC. However, the use of the __progmem__ attribute on a variable declaration is supported, and this is now the recommended usage.

The typedef is only visible if the macro __PROG_TYPES_COMPAT__ has been defined before including <avr/pgmspace.h> (either by a #define directive, or by a -D compiler option.)

Type of a 'char' object located in flash ROM.

prog_int16_t

Note:

: DEPRECATED

The typedef is only visible if the macro __PROG_TYPES_COMPAT__ has been defined before including <avr/pgmspace.h> (either by a #define directive, or by a -D compiler option.)

Type of an 'int16_t' object located in flash ROM.

prog_int32_t

Note:

: DEPRECATED

The typedef is only visible if the macro __PROG_TYPES_COMPAT__ has been defined before including <avr/pgmspace.h> (either by a #define directive, or by a -D compiler option.)

Type of an 'int32_t' object located in flash ROM.

prog_int64_t

Note:

: DEPRECATED

The typedef is only visible if the macro __PROG_TYPES_COMPAT__ has been defined before including <avr/pgmspace.h> (either by a #define directive, or by a -D compiler option.)

Type of an 'int64_t' object located in flash ROM.

Note:

: This type is not available when the compiler option -mint8 is in effect.

prog_int8_t

Note:

: DEPRECATED

The typedef is only visible if the macro __PROG_TYPES_COMPAT__ has been defined before including <avr/pgmspace.h> (either by a #define directive, or by a -D compiler option.)

Type of an 'int8_t' object located in flash ROM.

prog_uchar

Note:

: DEPRECATED

The typedef is only visible if the macro __PROG_TYPES_COMPAT__ has been defined before including <avr/pgmspace.h> (either by a #define directive, or by a -D compiler option.)

Type of an 'unsigned char' object located in flash ROM.

prog_uint16_t

Note:

: DEPRECATED

The typedef is only visible if the macro __PROG_TYPES_COMPAT__ has been defined before including <avr/pgmspace.h> (either by a #define directive, or by a -D compiler option.)

Type of an 'uint16_t' object located in flash ROM.

prog_uint32_t

Note:

: DEPRECATED

The typedef is only visible if the macro __PROG_TYPES_COMPAT__ has been defined before including <avr/pgmspace.h> (either by a #define directive, or by a -D compiler option.)

Type of an 'uint32_t' object located in flash ROM.

prog_uint64_t

Note:

: DEPRECATED

The typedef is only visible if the macro __PROG_TYPES_COMPAT__ has been defined before including <avr/pgmspace.h> (either by a #define directive, or by a -D compiler option.)

Type of an 'uint64_t' object located in flash ROM.

Note:

: This type is not available when the compiler option -mint8 is in effect.

prog_uint8_t

Note:

: DEPRECATED

The typedef is only visible if the macro __PROG_TYPES_COMPAT__ has been defined before including <avr/pgmspace.h> (either by a #define directive, or by a -D compiler option.)

Type of an 'uint8_t' object located in flash ROM.

prog_void

Note:

: DEPRECATED

The typedef is only visible if the macro __PROG_TYPES_COMPAT__ has been defined before including <avr/pgmspace.h> (either by a #define directive, or by a -D compiler option.)

Type of a 'void' object located in flash ROM. Does not make much sense by itself, but can be used to declare a 'void *' object in flash ROM.

Function Documentation

void * memccpy_P (void * dest, const void * src, int val, size_t len)

This function is similar to memccpy() except that src is pointer to a string in program space.

const void * memchr_P (const void * s, int val, size_t len)

Scan flash memory for a character. The memchr_P() function scans the first len bytes of the flash memory area pointed to by s for the character val. The first byte to match val (interpreted as an unsigned character) stops the operation.

Returns:

: The memchr_P() function returns a pointer to the matching byte or NULL if the character does not occur in the given memory area.

int memcmp_P (const void * s1, const void * s2, size_t len)

Compare memory areas. The memcmp_P() function compares the first len bytes of the memory areas s1 and flash s2. The comparision is performed using unsigned char operations.

Returns:

: The memcmp_P() function returns an integer less than, equal to, or greater than zero if the first len bytes of s1 is found, respectively, to be less than, to match, or be greater than the first len bytes of s2.

int memcmp_PF (const void * s1, uint_farptr_t s2, size_t len)

Compare memory areas. The memcmp_PF() function compares the first len bytes of the memory areas s1 and flash s2. The comparision is performed using unsigned char operations. It is an equivalent of memcmp_P() function, except that it is capable working on all FLASH including the exteded area above 64kB.

Returns:

: The memcmp_PF() function returns an integer less than, equal to, or greater than zero if the first len bytes of s1 is found, respectively, to be less than, to match, or be greater than the first len bytes of s2.

void * memcpy_P (void * dest, const void * src, size_t n)

The memcpy_P() function is similar to memcpy(), except the src string resides in program space.

Returns:

: The memcpy_P() function returns a pointer to dest.

void * memcpy_PF (void * dest, uint_farptr_t src, size_t n)

Copy a memory block from flash to SRAM. The memcpy_PF() function is similar to memcpy(), except the data is copied from the program space and is addressed using a far pointer.

Parameters:

: dest A pointer to the destination buffer
src A far pointer to the origin of data in flash memory
n The number of bytes to be copied

Returns:

: The memcpy_PF() function returns a pointer to dst. The contents of RAMPZ SFR are undefined when the function returns.

void * memmem_P (const void * s1, size_t len1, const void * s2, size_t len2)

The memmem_P() function is similar to memmem() except that s2 is pointer to a string in program space.

const void memrchr_P (const void * src, int val, size_t len)

The memrchr_P() function is like the memchr_P() function, except that it searches backwards from the end of the len bytes pointed to by src instead of forwards from the front. (Glibc, GNU extension.)

Returns:

: The memrchr_P() function returns a pointer to the matching byte or NULL if the character does not occur in the given memory area.

int strcasecmp_P (const char * s1, const char * s2)

Compare two strings ignoring case. The strcasecmp_P() function compares the two strings s1 and s2, ignoring the case of the characters.

Parameters:

: s1 A pointer to a string in the devices SRAM.
s2 A pointer to a string in the devices Flash.

Returns:

: The strcasecmp_P() function returns an integer less than, equal to, or greater than zero if s1 is found, respectively, to be less than, to match, or be greater than s2. A consequence of the ordering used by strcasecmp_P() is that if s1 is an initial substring of s2, then s1 is considered to be 'less than' s2.

int strcasecmp_PF (const char * s1, uint_farptr_t s2)

Compare two strings ignoring case. The strcasecmp_PF() function compares the two strings s1 and s2, ignoring the case of the characters.

Parameters:

: s1 A pointer to the first string in SRAM
s2 A far pointer to the second string in Flash

Returns:

: The strcasecmp_PF() function returns an integer less than, equal to, or greater than zero if s1 is found, respectively, to be less than, to match, or be greater than s2. The contents of RAMPZ SFR are undefined when the function returns.

char * strcasestr_P (const char * s1, const char * s2)

This funtion is similar to strcasestr() except that s2 is pointer to a string in program space.

char * strcat_P (char * dest, const char * src)

The strcat_P() function is similar to strcat() except that the src string must be located in program space (flash).

Returns:

: The strcat() function returns a pointer to the resulting string dest.

char * strcat_PF (char * dst, uint_farptr_t src)

Concatenates two strings. The strcat_PF() function is similar to strcat() except that the src string must be located in program space (flash) and is addressed using a far pointer

Parameters:

: dst A pointer to the destination string in SRAM
src A far pointer to the string to be appended in Flash

Returns:

: The strcat_PF() function returns a pointer to the resulting string dst. The contents of RAMPZ SFR are undefined when the function returns

const char * strchr_P (const char * s, int val)

Locate character in program space string. The strchr_P() function locates the first occurrence of val (converted to a char) in the string pointed to by s in program space. The terminating null character is considered to be part of the string.

The strchr_P() function is similar to strchr() except that s is pointer to a string in program space.

Returns:

: The strchr_P() function returns a pointer to the matched character or NULL if the character is not found.

const char * strchrnul_P (const char * s, int c)

The strchrnul_P() function is like strchr_P() except that if c is not found in s, then it returns a pointer to the null byte at the end of s, rather than NULL. (Glibc, GNU extension.)

Returns:

: The strchrnul_P() function returns a pointer to the matched character, or a pointer to the null byte at the end of s (i.e., s+strlen(s)) if the character is not found.

int strcmp_P (const char * s1, const char * s2)

The strcmp_P() function is similar to strcmp() except that s2 is pointer to a string in program space.

Returns:

: The strcmp_P() function returns an integer less than, equal to, or greater than zero if s1 is found, respectively, to be less than, to match, or be greater than s2. A consequence of the ordering used by strcmp_P() is that if s1 is an initial substring of s2, then s1 is considered to be 'less than' s2.

int strcmp_PF (const char * s1, uint_farptr_t s2)

Compares two strings. The strcmp_PF() function is similar to strcmp() except that s2 is a far pointer to a string in program space.

Parameters:

: s1 A pointer to the first string in SRAM
s2 A far pointer to the second string in Flash

Returns:

: The strcmp_PF() function returns an integer less than, equal to, or greater than zero if s1 is found, respectively, to be less than, to match, or be greater than s2. The contents of RAMPZ SFR are undefined when the function returns.

char * strcpy_P (char * dest, const char * src)

The strcpy_P() function is similar to strcpy() except that src is a pointer to a string in program space.

Returns:

: The strcpy_P() function returns a pointer to the destination string dest.

char * strcpy_PF (char * dst, uint_farptr_t src)

Duplicate a string. The strcpy_PF() function is similar to strcpy() except that src is a far pointer to a string in program space.

Parameters:

: dst A pointer to the destination string in SRAM
src A far pointer to the source string in Flash

Returns:

: The strcpy_PF() function returns a pointer to the destination string dst. The contents of RAMPZ SFR are undefined when the funcion returns.

size_t strcspn_P (const char * s, const char * reject)

The strcspn_P() function calculates the length of the initial segment of s which consists entirely of characters not in reject. This function is similar to strcspn() except that reject is a pointer to a string in program space.

Returns:

: The strcspn_P() function returns the number of characters in the initial segment of s which are not in the string reject. The terminating zero is not considered as a part of string.

size_t strlcat_P (char * dst, const char * src, size_t siz)

Concatenate two strings. The strlcat_P() function is similar to strlcat(), except that the src string must be located in program space (flash).

Appends src to string dst of size siz (unlike strncat(), siz is the full size of dst, not space left). At most siz-1 characters will be copied. Always NULL terminates (unless siz <= strlen(dst)).

Returns:

: The strlcat_P() function returns strlen(src) + MIN(siz, strlen(initial dst)). If retval >= siz, truncation occurred.

size_t strlcat_PF (char * dst, uint_farptr_t src, size_t n)

Concatenate two strings. The strlcat_PF() function is similar to strlcat(), except that the src string must be located in program space (flash) and is addressed using a far pointer.

Appends src to string dst of size n (unlike strncat(), n is the full size of dst, not space left). At most n-1 characters will be copied. Always NULL terminates (unless n <= strlen(dst)).

Parameters:

: dst A pointer to the destination string in SRAM
src A far pointer to the source string in Flash
n The total number of bytes allocated to the destination string

Returns:

: The strlcat_PF() function returns strlen(src) + MIN(n, strlen(initial dst)). If retval >= n, truncation occurred. The contents of RAMPZ SFR are undefined when the funcion returns.

size_t strlcpy_P (char * dst, const char * src, size_t siz)

Copy a string from progmem to RAM. Copy src to string dst of size siz. At most siz-1 characters will be copied. Always NULL terminates (unless siz == 0). The strlcpy_P() function is similar to strlcpy() except that the src is pointer to a string in memory space.

Returns:

: The strlcpy_P() function returns strlen(src). If retval >= siz, truncation occurred.

size_t strlcpy_PF (char * dst, uint_farptr_t src, size_t siz)

Copy a string from progmem to RAM. Copy src to string dst of size siz. At most siz-1 characters will be copied. Always NULL terminates (unless siz == 0).

Returns:

: The strlcpy_PF() function returns strlen(src). If retval >= siz, truncation occurred. The contents of RAMPZ SFR are undefined when the function returns.

size_t strlen_P (const char * src) [static]

The strlen_P() function is similar to strlen(), except that src is a pointer to a string in program space.

Returns:

: The strlen_P() function returns the number of characters in src.

Note:

: strlen_P() is implemented as an inline function in the avr/pgmspace.h header file, which will check if the length of the string is a constant and known at compile time. If it is not known at compile time, the macro will issue a call to __strlen_P() which will then calculate the length of the string as normal.

size_t strlen_PF (uint_farptr_t s)

Obtain the length of a string. The strlen_PF() function is similar to strlen(), except that s is a far pointer to a string in program space.

Parameters:

: s A far pointer to the string in flash

Returns:

: The strlen_PF() function returns the number of characters in s. The contents of RAMPZ SFR are undefined when the function returns.

int strncasecmp_P (const char * s1, const char * s2, size_t n)

Compare two strings ignoring case. The strncasecmp_P() function is similar to strcasecmp_P(), except it only compares the first n characters of s1.

Parameters:

: s1 A pointer to a string in the devices SRAM.
s2 A pointer to a string in the devices Flash.
n The maximum number of bytes to compare.

Returns:

: The strncasecmp_P() function returns an integer less than, equal to, or greater than zero if s1 (or the first n bytes thereof) is found, respectively, to be less than, to match, or be greater than s2. A consequence of the ordering used by strncasecmp_P() is that if s1 is an initial substring of s2, then s1 is considered to be 'less than' s2.

int strncasecmp_PF (const char * s1, uint_farptr_t s2, size_t n)

Compare two strings ignoring case. The strncasecmp_PF() function is similar to strcasecmp_PF(), except it only compares the first n characters of s1 and the string in flash is addressed using a far pointer.

Parameters:

: s1 A pointer to a string in SRAM
s2 A far pointer to a string in Flash
n The maximum number of bytes to compare

Returns:

: The strncasecmp_PF() function returns an integer less than, equal to, or greater than zero if s1 (or the first n bytes thereof) is found, respectively, to be less than, to match, or be greater than s2. The contents of RAMPZ SFR are undefined when the function returns.

char * strncat_P (char * dest, const char * src, size_t len)

Concatenate two strings. The strncat_P() function is similar to strncat(), except that the src string must be located in program space (flash).

Returns:

: The strncat_P() function returns a pointer to the resulting string dest.

char * strncat_PF (char * dst, uint_farptr_t src, size_t n)

Concatenate two strings. The strncat_PF() function is similar to strncat(), except that the src string must be located in program space (flash) and is addressed using a far pointer.

Parameters:

: dst A pointer to the destination string in SRAM
src A far pointer to the source string in Flash
n The maximum number of bytes to append

Returns:

: The strncat_PF() function returns a pointer to the resulting string dst. The contents of RAMPZ SFR are undefined when the function returns.

int strncmp_P (const char * s1, const char * s2, size_t n)

The strncmp_P() function is similar to strcmp_P() except it only compares the first (at most) n characters of s1 and s2.

Returns:

: The strncmp_P() function returns an integer less than, equal to, or greater than zero if s1 (or the first n bytes thereof) is found, respectively, to be less than, to match, or be greater than s2.

int strncmp_PF (const char * s1, uint_farptr_t s2, size_t n)

Compare two strings with limited length. The strncmp_PF() function is similar to strcmp_PF() except it only compares the first (at most) n characters of s1 and s2.

Parameters:

: s1 A pointer to the first string in SRAM
s2 A far pointer to the second string in Flash
n The maximum number of bytes to compare

Returns:

: The strncmp_PF() function returns an integer less than, equal to, or greater than zero if s1 (or the first n bytes thereof) is found, respectively, to be less than, to match, or be greater than s2. The contents of RAMPZ SFR are undefined when the function returns.

char * strncpy_P (char * dest, const char * src, size_t n)

The strncpy_P() function is similar to strcpy_P() except that not more than n bytes of src are copied. Thus, if there is no null byte among the first n bytes of src, the result will not be null-terminated.

In the case where the length of src is less than that of n, the remainder of dest will be padded with nulls.

Returns:

: The strncpy_P() function returns a pointer to the destination string dest.

char * strncpy_PF (char * dst, uint_farptr_t src, size_t n)

Duplicate a string until a limited length. The strncpy_PF() function is similar to strcpy_PF() except that not more than n bytes of src are copied. Thus, if there is no null byte among the first n bytes of src, the result will not be null-terminated.

In the case where the length of src is less than that of n, the remainder of dst will be padded with nulls.

Parameters:

: dst A pointer to the destination string in SRAM
src A far pointer to the source string in Flash
n The maximum number of bytes to copy

Returns:

: The strncpy_PF() function returns a pointer to the destination string dst. The contents of RAMPZ SFR are undefined when the function returns.

size_t strnlen_P (const char * src, size_t len)

Determine the length of a fixed-size string. The strnlen_P() function is similar to strnlen(), except that src is a pointer to a string in program space.

Returns:

: The strnlen_P function returns strlen_P(src), if that is less than len, or len if there is no '\0' character among the first len characters pointed to by src.

size_t strnlen_PF (uint_farptr_t s, size_t len)

Determine the length of a fixed-size string. The strnlen_PF() function is similar to strnlen(), except that s is a far pointer to a string in program space.

Parameters:

: s A far pointer to the string in Flash
len The maximum number of length to return

Returns:

: The strnlen_PF function returns strlen_P(s), if that is less than len, or len if there is no '\0' character among the first len characters pointed to by s. The contents of RAMPZ SFR are undefined when the function returns.

char * strpbrk_P (const char * s, const char * accept)

The strpbrk_P() function locates the first occurrence in the string s of any of the characters in the flash string accept. This function is similar to strpbrk() except that accept is a pointer to a string in program space.

Returns:

: The strpbrk_P() function returns a pointer to the character in s that matches one of the characters in accept, or NULL if no such character is found. The terminating zero is not considered as a part of string: if one or both args are empty, the result will NULL.

const char * strrchr_P (const char * s, int val)

Locate character in string. The strrchr_P() function returns a pointer to the last occurrence of the character val in the flash string s.

Returns:

: The strrchr_P() function returns a pointer to the matched character or NULL if the character is not found.

char * strsep_P (char ** sp, const char * delim)

Parse a string into tokens. The strsep_P() function locates, in the string referenced by *sp, the first occurrence of any character in the string delim (or the terminating '\0' character) and replaces it with a '\0'. The location of the next character after the delimiter character (or NULL, if the end of the string was reached) is stored in *sp. An ``empty'' field, i.e. one caused by two adjacent delimiter characters, can be detected by comparing the location referenced by the pointer returned in *sp to '\0'. This function is similar to strsep() except that delim is a pointer to a string in program space.

Returns:

: The strsep_P() function returns a pointer to the original value of *sp. If *sp is initially NULL, strsep_P() returns NULL.

size_t strspn_P (const char * s, const char * accept)

The strspn_P() function calculates the length of the initial segment of s which consists entirely of characters in accept. This function is similar to strspn() except that accept is a pointer to a string in program space.

Returns:

: The strspn_P() function returns the number of characters in the initial segment of s which consist only of characters from accept. The terminating zero is not considered as a part of string.

char * strstr_P (const char * s1, const char * s2)

Locate a substring. The strstr_P() function finds the first occurrence of the substring s2 in the string s1. The terminating '\0' characters are not compared. The strstr_P() function is similar to strstr() except that s2 is pointer to a string in program space.

Returns:

: The strstr_P() function returns a pointer to the beginning of the substring, or NULL if the substring is not found. If s2 points to a string of zero length, the function returns s1.

char * strstr_PF (const char * s1, uint_farptr_t s2)

Locate a substring. The strstr_PF() function finds the first occurrence of the substring s2 in the string s1. The terminating '\0' characters are not compared. The strstr_PF() function is similar to strstr() except that s2 is a far pointer to a string in program space.

Returns:

: The strstr_PF() function returns a pointer to the beginning of the substring, or NULL if the substring is not found. If s2 points to a string of zero length, the function returns s1. The contents of RAMPZ SFR are undefined when the function returns.

char * strtok_P (char * s, const char * delim)

Parses the string into tokens. strtok_P() parses the string s into tokens. The first call to strtok_P() should have s as its first argument. Subsequent calls should have the first argument set to NULL. If a token ends with a delimiter, this delimiting character is overwritten with a '\0' and a pointer to the next character is saved for the next call to strtok_P(). The delimiter string delim may be different for each call.

The strtok_P() function is similar to strtok() except that delim is pointer to a string in program space.

Returns:

: The strtok_P() function returns a pointer to the next token or NULL when no more tokens are found.

Note:

: strtok_P() is NOT reentrant. For a reentrant version of this function see strtok_rP().

char * strtok_rP (char * string, const char * delim, char ** last)

Parses string into tokens. The strtok_rP() function parses string into tokens. The first call to strtok_rP() should have string as its first argument. Subsequent calls should have the first argument set to NULL. If a token ends with a delimiter, this delimiting character is overwritten with a '\0' and a pointer to the next character is saved for the next call to strtok_rP(). The delimiter string delim may be different for each call. last is a user allocated char* pointer. It must be the same while parsing the same string. strtok_rP() is a reentrant version of strtok_P().

The strtok_rP() function is similar to strtok_r() except that delim is pointer to a string in program space.

Returns:

: The strtok_rP() function returns a pointer to the next token or NULL when no more tokens are found.

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