utf8_p.h File Reference

Go to the source code of this file.

Functions
static uint32_t	get_utf8 (const uint8_t **buffer, const uint8_t *end)

Function Documentation

get_utf8()

static uint32_t get_utf8 ( const uint8_t **  buffer, const uint8_t *  end  )

static

Definition at line 32 of file utf8_p.h.

{
    int charsNeeded;
    uint32_t uc, min_uc;
    uint8_t b;
    ptrdiff_t n = end - *buffer;
    if (n == 0)
        return ~0U;
 
    uc = *(*buffer)++;
    if (uc < 0x80) {
        /* single-byte UTF-8 */
        return uc;
    }
 
    /* multi-byte UTF-8, decode it */
    if (unlikely(uc <= 0xC1))
        return ~0U;
    if (uc < 0xE0) {
        /* two-byte UTF-8 */
        charsNeeded = 2;
        min_uc = 0x80;
        uc &= 0x1f;
    } else if (uc < 0xF0) {
        /* three-byte UTF-8 */
        charsNeeded = 3;
        min_uc = 0x800;
        uc &= 0x0f;
    } else if (uc < 0xF5) {
        /* four-byte UTF-8 */
        charsNeeded = 4;
        min_uc = 0x10000;
        uc &= 0x07;
    } else {
        return ~0U;
    }
 
    if (n < charsNeeded - 1)
        return ~0U;
 
    /* first continuation character */
    b = *(*buffer)++;
    if ((b & 0xc0) != 0x80)
        return ~0U;
    uc <<= 6;
    uc |= b & 0x3f;
 
    if (charsNeeded > 2) {
        /* second continuation character */
        b = *(*buffer)++;
        if ((b & 0xc0) != 0x80)
            return ~0U;
        uc <<= 6;
        uc |= b & 0x3f;
 
        if (charsNeeded > 3) {
            /* third continuation character */
            b = *(*buffer)++;
            if ((b & 0xc0) != 0x80)
                return ~0U;
            uc <<= 6;
            uc |= b & 0x3f;
        }
    }
 
    /* overlong sequence? surrogate pair? out or range? */
    if (uc < min_uc || uc - 0xd800U < 2048U || uc > 0x10ffff)
        return ~0U;
 
    return uc;
}