const uint16_t *
u16_grapheme_prev (const uint16_t *s, const uint16_t *start)
{
ucs4_t next;
if (s == start)
return NULL;
s = u16_prev (&next, s, start);
while (s != start)
{
const uint16_t *prev_s;
ucs4_t prev;
prev_s = u16_prev (&prev, s, start);
if (prev_s == NULL)
{
/* Ill-formed UTF-16 encoding. */
return start;
}
if (uc_is_grapheme_break (prev, next))
break;
s = prev_s;
next = prev;
}
return s;
}
static int
check_invalid (const uint16_t *input, size_t input_length)
{
ucs4_t uc;
/* Test recognition when at the beginning of the string. */
uc = 0xBADFACE;
if (u16_prev (&uc, input + input_length, input) != NULL)
return 1;
if (uc != 0xBADFACE)
return 2;
#if CONFIG_UNICODE_SAFETY
/* Test recognition when preceded by a 1-unit character. */
{
uint16_t buf[100];
uint16_t *ptr;
size_t i;
ptr = buf;
*ptr++ = 0x2102;
for (i = 0; i < input_length; i++)
ptr[i] = input[i];
uc = 0xBADFACE;
if (u16_prev (&uc, ptr + input_length, buf) != NULL)
return 3;
if (uc != 0xBADFACE)
return 4;
}
/* Test recognition when preceded by a 2-unit character. */
{
uint16_t buf[100];
uint16_t *ptr;
size_t i;
ptr = buf;
*ptr++ = 0xD835;
*ptr++ = 0xDD1E;
for (i = 0; i < input_length; i++)
ptr[i] = input[i];
uc = 0xBADFACE;
if (u16_prev (&uc, ptr + input_length, buf) != NULL)
return 5;
if (uc != 0xBADFACE)
return 6;
}
#endif
return 0;
}
static int
check (const uint16_t *input, size_t input_length, ucs4_t *puc)
{
ucs4_t uc;
/* Test recognition when at the beginning of the string. */
if (u16_prev (&uc, input + input_length, input) != input)
return 1;
/* Test recognition when preceded by a 1-unit character. */
{
uint16_t buf[100];
uint16_t *ptr;
size_t i;
ucs4_t uc1;
ptr = buf;
*ptr++ = 0x2102;
for (i = 0; i < input_length; i++)
ptr[i] = input[i];
if (u16_prev (&uc1, ptr + input_length, buf) != ptr)
return 2;
if (uc1 != uc)
return 3;
}
/* Test recognition when preceded by a 2-unit character. */
{
uint16_t buf[100];
uint16_t *ptr;
size_t i;
ucs4_t uc1;
ptr = buf;
*ptr++ = 0xD835;
*ptr++ = 0xDD1E;
for (i = 0; i < input_length; i++)
ptr[i] = input[i];
if (u16_prev (&uc1, ptr + input_length, buf) != ptr)
return 4;
if (uc1 != uc)
return 5;
}
*puc = uc;
return 0;
}
