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utf16_literal_to_utf8: Eliminate Duff's Device

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This fixes -Wimplicit-fallthrough warnings with GCC7.
This commit is contained in:
Max Bruckner 2017-03-02 13:46:31 +01:00
parent ad5abf4c5b
commit 9d07917feb
1 changed files with 19 additions and 30 deletions
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49
cJSON.c
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@ -452,21 +452,13 @@ static unsigned parse_hex4(const unsigned char * const input)
* A literal can be one or two sequences of the form \uXXXX */ * A literal can be one or two sequences of the form \uXXXX */
static unsigned char utf16_literal_to_utf8(const unsigned char * const input_pointer, const unsigned char * const input_end, unsigned char **output_pointer, const unsigned char **error_pointer) static unsigned char utf16_literal_to_utf8(const unsigned char * const input_pointer, const unsigned char * const input_end, unsigned char **output_pointer, const unsigned char **error_pointer)
{ {
/* first bytes of UTF8 encoding for a given length in bytes */
static const unsigned char firstByteMark[5] =
{
0x00, /* should never happen */
0x00, /* 0xxxxxxx */
0xC0, /* 110xxxxx */
0xE0, /* 1110xxxx */
0xF0 /* 11110xxx */
};
long unsigned int codepoint = 0; long unsigned int codepoint = 0;
unsigned int first_code = 0; unsigned int first_code = 0;
const unsigned char *first_sequence = input_pointer; const unsigned char *first_sequence = input_pointer;
unsigned char utf8_length = 0; unsigned char utf8_length = 0;
unsigned char utf8_position = 0;
unsigned char sequence_length = 0; unsigned char sequence_length = 0;
unsigned char first_byte_mark = 0;
/* get the first utf16 sequence */ /* get the first utf16 sequence */
first_code = parse_hex4(first_sequence + 2); first_code = parse_hex4(first_sequence + 2);
@ -537,16 +529,19 @@ static unsigned char utf16_literal_to_utf8(const unsigned char * const input_poi
{ {
/* two bytes, encoding 110xxxxx 10xxxxxx */ /* two bytes, encoding 110xxxxx 10xxxxxx */
utf8_length = 2; utf8_length = 2;
first_byte_mark = 0xC0; /* 11000000 */
} }
else if (codepoint < 0x10000) else if (codepoint < 0x10000)
{ {
/* three bytes, encoding 1110xxxx 10xxxxxx 10xxxxxx */ /* three bytes, encoding 1110xxxx 10xxxxxx 10xxxxxx */
utf8_length = 3; utf8_length = 3;
first_byte_mark = 0xE0; /* 11100000 */
} }
else if (codepoint <= 0x10FFFF) else if (codepoint <= 0x10FFFF)
{ {
/* four bytes, encoding 1110xxxx 10xxxxxx 10xxxxxx 10xxxxxx */ /* four bytes, encoding 1110xxxx 10xxxxxx 10xxxxxx 10xxxxxx */
utf8_length = 4; utf8_length = 4;
first_byte_mark = 0xF0; /* 11110000 */
} }
else else
{ {
@ -556,28 +551,22 @@ static unsigned char utf16_literal_to_utf8(const unsigned char * const input_poi
} }
/* encode as utf8 */ /* encode as utf8 */
switch (utf8_length) for (utf8_position = (unsigned char)(utf8_length - 1); utf8_position > 0; utf8_position--)
{ {
case 4: /* 10xxxxxx */
/* 10xxxxxx */ (*output_pointer)[utf8_position] = (unsigned char)((codepoint | 0x80) & 0xBF);
(*output_pointer)[3] = (unsigned char)((codepoint | 0x80) & 0xBF); codepoint >>= 6;
codepoint >>= 6;
case 3:
/* 10xxxxxx */
(*output_pointer)[2] = (unsigned char)((codepoint | 0x80) & 0xBF);
codepoint >>= 6;
case 2:
(*output_pointer)[1] = (unsigned char)((codepoint | 0x80) & 0xBF);
codepoint >>= 6;
case 1:
/* depending on the length in bytes this determines the
encoding of the first UTF8 byte */
(*output_pointer)[0] = (unsigned char)((codepoint | firstByteMark[utf8_length]) & 0xFF);
break;
default:
*error_pointer = first_sequence;
goto fail;
} }
/* encode first byte */
if (utf8_length > 1)
{
(*output_pointer)[0] = (unsigned char)((codepoint | first_byte_mark) & 0xFF);
}
else
{
(*output_pointer)[0] = (unsigned char)(codepoint & 0x7F);
}
*output_pointer += utf8_length; *output_pointer += utf8_length;
return sequence_length; return sequence_length;