📄 lib_str.c
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* Argument(s) : p1_str Pointer to first string (see Note #1).
*
* p2_str Pointer to second string (see Note #1).
*
* len_max Maximum number of characters to compare (see Notes #2i & #2j).
*
* Return(s) : 0, if strings are identical (see Notes #2a, #2e, #2f, #2i, & #2j).
*
* Negative value, if 'p1_str' is less than 'p2_str' (see Notes #2b, #2g, & #2d).
*
* Positive value, if 'p1_str' is greater than 'p2_str' (see Notes #2c, #2h, & #2d).
*
* Caller(s) : various.
*
* Note(s) : (1) String buffers NOT modified.
*
* (2) String comparison terminates when :
*
* (a) BOTH string pointer(s) are passed NULL pointers.
* (1) NULL strings identical; return 0.
*
* (b) 'p1_str' passed a NULL pointer.
* (1) Return negative value of character pointed to by 'p2_str'.
*
* (c) 'p2_str' passed a NULL pointer.
* (1) Return positive value of character pointed to by 'p1_str'.
*
* (d) Non-matching characters found.
* (1) Return signed-integer difference of the character pointed to by 'p2_str'
* from the character pointed to by 'p1_str'.
*
* (e) Terminating NULL character found in both strings.
* (1) Strings identical; return 0.
* (2) Only one NULL character test required in conditional since previous condition
* tested character equality.
*
* (f) BOTH strings point to NULL.
* (1) Strings overlap with NULL address.
* (2) Strings identical up to but NOT beyond or including the NULL address; return 0.
*
* (g) 'p1_str_next' points to NULL.
* (1) 'p1_str' overlaps with NULL address.
* (2) Strings compared up to but NOT beyond or including the NULL address.
* (3) Return negative value of character pointed to by 'p2_str_next'.
*
* (h) 'p2_str_next' points to NULL.
* (1) 'p2_str' overlaps with NULL address.
* (2) Strings compared up to but NOT beyond or including the NULL address.
* (3) Return positive value of character pointed to by 'p1_str_next'.
*
* (i) 'len_max' passed a zero length.
* (1) Zero-length strings identical; return 0.
*
* (j) First 'len_max' number of characters identical.
* (1) Strings identical; return 0.
*
* (3) Since 16-bit signed arithmetic is performed to calculate a non-identical comparison
* return value, 'CPU_CHAR' native data type size MUST be 8-bit.
*********************************************************************************************************
*/
/*$PAGE*/
CPU_INT16S Str_Cmp_N (CPU_CHAR *p1_str,
CPU_CHAR *p2_str,
CPU_SIZE_T len_max)
{
CPU_CHAR *p1_str_next;
CPU_CHAR *p2_str_next;
CPU_INT16S cmp_val;
CPU_SIZE_T cmp_len;
if (len_max == 0) { /* If cmp len equals zero, rtn 0 (see Note #2i). */
return ((CPU_INT16S)0);
}
if (p1_str == (CPU_CHAR *)0) {
if (p2_str == (CPU_CHAR *)0) {
return ((CPU_INT16S)0); /* If BOTH str ptrs NULL, rtn 0 (see Note #2a). */
}
cmp_val = (CPU_INT16S)0 - (CPU_INT16S)(*p2_str);
return (cmp_val); /* If p1_str NULL, rtn neg p2_str val (see Note #2b). */
}
if (p2_str == (CPU_CHAR *)0) {
cmp_val = (CPU_INT16S)(*p1_str);
return (cmp_val); /* If p2_str NULL, rtn pos p1_str val (see Note #2c). */
}
p1_str_next = p1_str;
p2_str_next = p2_str;
p1_str_next++;
p2_str_next++;
cmp_len = 0;
while ((*p1_str == *p2_str) && /* Cmp strs until non-matching char (see Note #2d) .. */
(*p1_str != (CPU_CHAR )0) && /* .. or NULL char(s) (see Note #2e) .. */
( p1_str_next != (CPU_CHAR *)0) && /* .. or NULL ptr(s) found (see Notes #2f, #2g, & #2h); */
( p2_str_next != (CPU_CHAR *)0) &&
( cmp_len < (CPU_SIZE_T)len_max)) { /* .. or len nbr chars cmp'd (see Note #2j). */
p1_str_next++;
p2_str_next++;
p1_str++;
p2_str++;
cmp_len++;
}
if (cmp_len == len_max) { /* If strs identical for len nbr of chars, */
return ((CPU_INT16S)0); /* ... rtn 0 (see Note #2j). */
}
if (*p1_str != *p2_str) { /* If strs NOT identical, ... */
cmp_val = (CPU_INT16S)(*p1_str) - (CPU_INT16S)(*p2_str); /* ... calc & rtn char diff (see Note #2d1). */
} else if (*p1_str == (CPU_CHAR)0) { /* If NULL char(s) found, ... */
cmp_val = 0; /* ... strs identical; rtn 0 (see Note #2e). */
} else {
if (p1_str_next == (CPU_CHAR *)0) {
if (p2_str_next == (CPU_CHAR *)0) { /* If BOTH next str ptrs NULL, ... */
cmp_val = (CPU_INT16S)0; /* ... rtn 0 (see Note #2f). */
} else { /* If p1_str_next NULL, ... */
cmp_val = (CPU_INT16S)0 - (CPU_INT16S)(*p2_str_next); /* ... rtn neg p2_str_next val (see Note #2g). */
}
} else { /* If p2_str_next NULL, ... */
cmp_val = (CPU_INT16S)(*p1_str_next); /* ... rtn pos p1_str_next val (see Note #2h). */
}
}
return (cmp_val);
}
/*$PAGE*/
/*
*********************************************************************************************************
* Str_Char()
*
* Description : Search string for first occurrence of specific character.
*
* Argument(s) : pstr Pointer to string (see Note #1).
*
* srch_char Search character.
*
* Return(s) : Pointer to first occurrence of search character in string, if any.
*
* Pointer to NULL, otherwise.
*
* Caller(s) : various.
*
* Note(s) : (1) String buffer NOT modified.
*
* (2) String search terminates when :
*
* (a) String pointer passed a NULL pointer.
* (1) No string search performed; NULL pointer returned.
*
* (b) String pointer points to NULL.
* (1) String overlaps with NULL address.
* (2) String searched up to but NOT beyond or including the NULL address.
*
* (c) String's terminating NULL character found.
* (1) Search character NOT found in search string; NULL pointer returned.
* (2) Applicable ONLY IF search character is NOT the terminating NULL character.
*
* (d) Search character found.
* (1) Return pointer to first occurrence of search character in search string.
*********************************************************************************************************
*/
CPU_CHAR *Str_Char (CPU_CHAR *pstr,
CPU_CHAR srch_char)
{
CPU_CHAR *pstr_next;
if (pstr == (CPU_CHAR *)0) { /* Rtn NULL if srch str ptr NULL (see Note #2a). */
return ((CPU_CHAR *)0);
}
pstr_next = pstr;
pstr_next++;
while (( pstr_next != (CPU_CHAR *)0) && /* Srch str until NULL ptr(s) (see Note #2b) ... */
(*pstr != (CPU_CHAR )0) && /* ... or NULL char (see Note #2c) ... */
(*pstr != (CPU_CHAR )srch_char)) { /* ... or srch char found (see Note #2d). */
pstr++;
pstr_next++;
}
if (*pstr != srch_char) { /* If srch char NOT found, str points to NULL; ... */
return ((CPU_CHAR *)0); /* ... rtn NULL (see Notes #2b & #2c). */
}
return (pstr); /* Else rtn ptr to found srch char (see Note #2d). */
}
/*$PAGE*/
/*
*********************************************************************************************************
* Str_Char_N()
*
* Description : Search string for first occurrence of specific character, up to a maximum number of characters.
*
* Argument(s) : pstr Pointer to string (see Note #1).
*
* len_max Maximum number of characters to search (see Notes #2e & #3).
*
* srch_char Search character.
*
* Return(s) : Pointer to first occurrence of search character in string, if any.
*
* Pointer to NULL, otherwise.
*
* Caller(s) : various.
*
* Note(s) : (1) String buffer NOT modified.
*
* (2) String search terminates when :
*
* (a) String pointer passed a NULL pointer.
* (1) No string search performed; NULL pointer returned.
*
* (b) String pointer points to NULL.
* (1) String overlaps with NULL address.
* (2) String searched up to but NOT beyond or including the NULL address.
*
* (c) String's terminating NULL character found.
* (1) Search character NOT found in search string; NULL pointer returned.
* (2) Applicable ONLY IF search character is NOT the terminating NULL character.
*
* (d) Search character found.
* (1) Return pointer to first occurrence of search character in search string.
*
* (e) 'len_max' number of characters searched.
* (1) 'len_max' number of characters does NOT include terminating NULL character.
*
* (3) Ideally, the 'len_max' parameter would be the last parameter in this function's
* paramter list for consistency with all other custom string library functions.
* However, the 'len_max' parameter is ordered to comply with the standard library
* function's parameter list.
*********************************************************************************************************
*/
CPU_CHAR *Str_Char_N (CPU_CHAR *pstr,
CPU_SIZE_T len_max,
CPU_CHAR srch_char)
{
CPU_CHAR *pstr_next;
CPU_SIZE_T len_srch;
if (pstr == (CPU_CHAR *)0) { /* Rtn NULL if srch str ptr NULL (see Note #2a). */
return ((CPU_CHAR *)0);
}
if (len_max == (CPU_SIZE_T)0) { /* Rtn NULL if srch len equals zero (see Note #2e). */
return ((CPU_CHAR *)0);
}
pstr_next = pstr;
pstr_next++;
len_srch = 0;
while (( pstr_next != (CPU_CHAR *)0) && /* Srch str until NULL ptr(s) (see Note #2b) ... */
(*pstr != (CPU_CHAR )0) && /* ... or NULL char (see Note #2c) ... */
(*pstr != (CPU_CHAR )srch_char) && /* ... or srch char found (see Note #2d); ... */
( len_srch < (CPU_SIZE_T)len_max)) { /* ... or max nbr chars srch'd (see Note #2e). */
pstr++;
pstr_next++;
len_srch++;
}
if (*pstr != srch_char) { /* If srch char NOT found, str points to NULL; ... */
return ((CPU_CHAR *)0); /* ... rtn NULL (see Notes #2b & #2c). */
}
return (pstr); /* Else rtn ptr to found srch char (see Note #2d). */
}
/*$PAGE*/
/*
*********************************************************************************************************
* Str_Char_Last()
*
* Description : Search string for last occurrence of specific character.
*
* Argument(s) : pstr Pointer to string (see Note #1).
*
* srch_char Search character.
*
* Return(s) : Pointer to last occurrence of search character in string, if any.
*
* Pointer to NULL, otherwise.
*
* Caller(s) : various.
*
* Note(s) : (1) String buffer NOT modified.
*
* (2) String search terminates when :
*
* (a) String pointer passed a NULL pointer.
* (1) No string search performed; NULL pointer returned.
*
* (b) String pointer points to NULL.
* (1) String overlaps with NULL address.
* (2) String searched up to but NOT beyond or including the NULL address.
* (3) NULL address boundary handled in Str_Len().
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