diff options
| -rw-r--r-- | libass/ass.c | 38 |
1 files changed, 16 insertions, 22 deletions
diff --git a/libass/ass.c b/libass/ass.c index d99498e..cdaf66e 100644 --- a/libass/ass.c +++ b/libass/ass.c @@ -659,24 +659,18 @@ static int process_events_line(ASS_Track *track, char *str) return 0; } -// Copied from mkvtoolnix -static unsigned char *decode_chars(unsigned char c1, unsigned char c2, - unsigned char c3, unsigned char c4, - unsigned char *dst, int cnt) +static unsigned char *decode_chars(const unsigned char *src, + unsigned char *dst, int cnt_in) { - uint32_t value; - unsigned char bytes[3]; - int i; - - value = - ((c1 - 33) << 18) + ((c2 - 33) << 12) + ((c3 - 33) << 6) + (c4 - - 33); - bytes[2] = value & 0xff; - bytes[1] = (value & 0xff00) >> 8; - bytes[0] = (value & 0xff0000) >> 16; - - for (i = 0; i < cnt; ++i) - *dst++ = bytes[i]; + uint32_t value = 0; + for (int i = 0; i < cnt_in; i++) + value |= (uint32_t) ((src[i] - 33u) & 63) << 6 * (3 - i); + + *dst++ = value >> 16; + if (cnt_in >= 3) + *dst++ = value >> 8 & 0xff; + if (cnt_in >= 4) + *dst++ = value & 0xff; return dst; } @@ -696,21 +690,21 @@ static int decode_font(ASS_Track *track) ass_msg(track->library, MSGL_ERR, "Bad encoded data size"); goto error_decode_font; } - buf = malloc(size / 4 * 3 + 2); + buf = malloc(size / 4 * 3 + FFMAX(size % 4 - 1, 0)); if (!buf) goto error_decode_font; q = buf; for (i = 0, p = (unsigned char *) track->parser_priv->fontdata; i < size / 4; i++, p += 4) { - q = decode_chars(p[0], p[1], p[2], p[3], q, 3); + q = decode_chars(p, q, 4); } if (size % 4 == 2) { - q = decode_chars(p[0], p[1], 0, 0, q, 1); + q = decode_chars(p, q, 2); } else if (size % 4 == 3) { - q = decode_chars(p[0], p[1], p[2], 0, q, 2); + q = decode_chars(p, q, 3); } dsize = q - buf; - assert(dsize <= size / 4 * 3 + 2); + assert(dsize == size / 4 * 3 + FFMAX(size % 4 - 1, 0)); if (track->library->extract_fonts) { ass_add_font(track->library, track->parser_priv->fontname, |