#ifndef VLIBC_STRINGS_H
#define VLIBC_STRINGS_H

/*
 * vlibc — <strings.h>.
 *
 * BSD/XSI legacy string functions, gated by the active compatibility
 * profile (see include/vlibc/features.h). This ENTIRE header is a legacy
 * extension: nothing it declares is POSIX.1-2008 base, so at level 1
 * (onlyposix) it is empty. POSIX mandates that <strings.h> (BSD legacy)
 * and <string.h> (ISO C) remain separate headers; the two never share a
 * declaration, so including both can never conflict.
 *
 *   strcasecmp / strncasecmp — XSI case-insensitive comparisons (ASCII
 *                              'A'..'Z'/'a'..'z' fold only, byte-wise);
 *   ffs / ffsl / ffsll       — XSI find-first-set-bit, 1-based;
 *   bcmp / bcopy / bzero     — BSD legacy byte operations (bcopy takes
 *                              (src, dst) — the arguments are REVERSED
 *                              relative to memcpy/memmove);
 *   index / rindex           — BSD legacy names for strchr / strrchr.
 *
 * This header includes <vlibc/features.h> itself, so the gate below always
 * sees the configured VLIBC_LEVEL even when the caller included no vlibc
 * header first, and <stddef.h> for size_t.
 */

#include <vlibc/features.h>

#if VLIBC_LEVEL_GE(2)

#include <stddef.h>

#ifdef __cplusplus
extern "C" {
#endif

/*
 * Compare s1 and s2 byte-wise, ignoring case: each byte is read as
 * unsigned char and an ASCII 'A'..'Z' is folded to 'a'..'z' before the
 * comparison; bytes at or above 0x80 pass through unmodified. Return
 * negative, zero, or positive when s1 is less than, equal to, or greater
 * than s2.
 * pure: reads memory, no side effects.
 */
__attribute__((pure)) int
strcasecmp(const char *s1, const char *s2);

/*
 * Compare at most n bytes of s1 and s2 as strcasecmp does, stopping early
 * at the first difference or the first NUL; return negative, zero, or
 * positive like strcasecmp. The NUL terminator of either string ends the
 * comparison even when n is larger.
 * pure: reads memory, no side effects.
 */
__attribute__((pure)) int
strncasecmp(const char *s1, const char *s2, size_t n);

/*
 * Return the 1-based index of the least significant set bit of i, or 0
 * when i has no set bit: ffs(0) == 0, ffs(1) == 1, ffs(8) == 4,
 * ffs(INT_MIN) == 32.
 * const: the result depends only on i.
 */
__attribute__((const)) int
ffs(int i);

/*
 * Same as ffs for long: ffsl(0) == 0, ffsl(1L << 40) == 41,
 * ffsl(LONG_MIN) == 64 (long is 64-bit on x86_64).
 * const: the result depends only on i.
 */
__attribute__((const)) int
ffsl(long i);

/*
 * Same as ffs for long long: ffsll(0) == 0, ffsll(LLONG_MIN) == 64.
 * const: the result depends only on i.
 */
__attribute__((const)) int
ffsll(long long i);

/*
 * Compare the first n bytes of s1 and s2 as unsigned char, like memcmp;
 * unlike strcmp a NUL byte does not end the comparison. Return 0 when the
 * n bytes are equal, nonzero otherwise.
 * pure: reads memory, no side effects.
 */
__attribute__((pure)) int
bcmp(const void *s1, const void *s2, size_t n);

/*
 * Copy n bytes from src to dst. The regions may overlap and the copy
 * behaves like memmove. NOTE the argument order: source first, destination
 * second — the reverse of memcpy/memmove.
 * No intent attribute: it writes memory.
 */
void
bcopy(const void *src, void *dst, size_t n);

/*
 * Fill n bytes at s with zero.
 * No intent attribute: it writes memory.
 */
void
bzero(void *s, size_t n);

/*
 * Return a pointer to the first occurrence of c (converted to unsigned
 * char) in s, or NULL when absent. The terminating NUL is part of the
 * string, so index(s, '\0') returns a pointer to it. Legacy name for
 * strchr.
 * pure: reads memory, no side effects.
 */
__attribute__((pure)) char *
index(const char *s, int c);

/*
 * Return a pointer to the last occurrence of c (converted to unsigned
 * char) in s, or NULL when absent. The terminating NUL is part of the
 * string, so rindex(s, '\0') returns a pointer to it. Legacy name for
 * strrchr.
 * pure: reads memory, no side effects.
 */
__attribute__((pure)) char *
rindex(const char *s, int c);

#ifdef __cplusplus
}
#endif

#endif /* VLIBC_LEVEL_GE(2) */

#endif /* VLIBC_STRINGS_H */