diff options
Diffstat (limited to '')
-rw-r--r-- | src/third-party/base64/lib/arch/ssse3/dec_loop.c | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/src/third-party/base64/lib/arch/ssse3/dec_loop.c b/src/third-party/base64/lib/arch/ssse3/dec_loop.c new file mode 100644 index 0000000..9da71ab --- /dev/null +++ b/src/third-party/base64/lib/arch/ssse3/dec_loop.c @@ -0,0 +1,173 @@ +// The input consists of six character sets in the Base64 alphabet, which we +// need to map back to the 6-bit values they represent. There are three ranges, +// two singles, and then there's the rest. +// +// # From To Add Characters +// 1 [43] [62] +19 + +// 2 [47] [63] +16 / +// 3 [48..57] [52..61] +4 0..9 +// 4 [65..90] [0..25] -65 A..Z +// 5 [97..122] [26..51] -71 a..z +// (6) Everything else => invalid input +// +// We will use lookup tables for character validation and offset computation. +// Remember that 0x2X and 0x0X are the same index for _mm_shuffle_epi8, this +// allows to mask with 0x2F instead of 0x0F and thus save one constant +// declaration (register and/or memory access). +// +// For offsets: +// Perfect hash for lut = ((src >> 4) & 0x2F) + ((src == 0x2F) ? 0xFF : 0x00) +// 0000 = garbage +// 0001 = / +// 0010 = + +// 0011 = 0-9 +// 0100 = A-Z +// 0101 = A-Z +// 0110 = a-z +// 0111 = a-z +// 1000 >= garbage +// +// For validation, here's the table. +// A character is valid if and only if the AND of the 2 lookups equals 0: +// +// hi \ lo 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 +// LUT 0x15 0x11 0x11 0x11 0x11 0x11 0x11 0x11 0x11 0x11 0x13 0x1A 0x1B 0x1B 0x1B 0x1A +// +// 0000 0x10 char NUL SOH STX ETX EOT ENQ ACK BEL BS HT LF VT FF CR SO SI +// andlut 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 +// +// 0001 0x10 char DLE DC1 DC2 DC3 DC4 NAK SYN ETB CAN EM SUB ESC FS GS RS US +// andlut 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 +// +// 0010 0x01 char ! " # $ % & ' ( ) * + , - . / +// andlut 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x01 0x00 0x01 0x01 0x01 0x00 +// +// 0011 0x02 char 0 1 2 3 4 5 6 7 8 9 : ; < = > ? +// andlut 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x02 0x02 0x02 0x02 0x02 0x02 +// +// 0100 0x04 char @ A B C D E F G H I J K L M N O +// andlut 0x04 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 +// +// 0101 0x08 char P Q R S T U V W X Y Z [ \ ] ^ _ +// andlut 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x08 0x08 0x08 0x08 0x08 +// +// 0110 0x04 char ` a b c d e f g h i j k l m n o +// andlut 0x04 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 +// 0111 0x08 char p q r s t u v w x y z { | } ~ +// andlut 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x08 0x08 0x08 0x08 0x08 +// +// 1000 0x10 andlut 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 +// 1001 0x10 andlut 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 +// 1010 0x10 andlut 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 +// 1011 0x10 andlut 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 +// 1100 0x10 andlut 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 +// 1101 0x10 andlut 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 +// 1110 0x10 andlut 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 +// 1111 0x10 andlut 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 0x10 + +static inline int +dec_loop_ssse3_inner (const uint8_t **s, uint8_t **o, size_t *rounds) +{ + const __m128i lut_lo = _mm_setr_epi8( + 0x15, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, + 0x11, 0x11, 0x13, 0x1A, 0x1B, 0x1B, 0x1B, 0x1A); + + const __m128i lut_hi = _mm_setr_epi8( + 0x10, 0x10, 0x01, 0x02, 0x04, 0x08, 0x04, 0x08, + 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10); + + const __m128i lut_roll = _mm_setr_epi8( + 0, 16, 19, 4, -65, -65, -71, -71, + 0, 0, 0, 0, 0, 0, 0, 0); + + const __m128i mask_2F = _mm_set1_epi8(0x2F); + + // Load input: + __m128i str = _mm_loadu_si128((__m128i *) *s); + + // Table lookups: + const __m128i hi_nibbles = _mm_and_si128(_mm_srli_epi32(str, 4), mask_2F); + const __m128i lo_nibbles = _mm_and_si128(str, mask_2F); + const __m128i hi = _mm_shuffle_epi8(lut_hi, hi_nibbles); + const __m128i lo = _mm_shuffle_epi8(lut_lo, lo_nibbles); + + // Check for invalid input: if any "and" values from lo and hi are not + // zero, fall back on bytewise code to do error checking and reporting: + if (_mm_movemask_epi8(_mm_cmpgt_epi8(_mm_and_si128(lo, hi), _mm_setzero_si128())) != 0) { + return 0; + } + + const __m128i eq_2F = _mm_cmpeq_epi8(str, mask_2F); + const __m128i roll = _mm_shuffle_epi8(lut_roll, _mm_add_epi8(eq_2F, hi_nibbles)); + + // Now simply add the delta values to the input: + str = _mm_add_epi8(str, roll); + + // Reshuffle the input to packed 12-byte output format: + str = dec_reshuffle(str); + + // Store the output: + _mm_storeu_si128((__m128i *) *o, str); + + *s += 16; + *o += 12; + *rounds -= 1; + + return 1; +} + +static inline void +dec_loop_ssse3 (const uint8_t **s, size_t *slen, uint8_t **o, size_t *olen) +{ + if (*slen < 24) { + return; + } + + // Process blocks of 16 bytes per round. Because 4 extra zero bytes are + // written after the output, ensure that there will be at least 8 bytes + // of input data left to cover the gap. (6 data bytes and up to two + // end-of-string markers.) + size_t rounds = (*slen - 8) / 16; + + *slen -= rounds * 16; // 16 bytes consumed per round + *olen += rounds * 12; // 12 bytes produced per round + + do { + if (rounds >= 8) { + if (dec_loop_ssse3_inner(s, o, &rounds) && + dec_loop_ssse3_inner(s, o, &rounds) && + dec_loop_ssse3_inner(s, o, &rounds) && + dec_loop_ssse3_inner(s, o, &rounds) && + dec_loop_ssse3_inner(s, o, &rounds) && + dec_loop_ssse3_inner(s, o, &rounds) && + dec_loop_ssse3_inner(s, o, &rounds) && + dec_loop_ssse3_inner(s, o, &rounds)) { + continue; + } + break; + } + if (rounds >= 4) { + if (dec_loop_ssse3_inner(s, o, &rounds) && + dec_loop_ssse3_inner(s, o, &rounds) && + dec_loop_ssse3_inner(s, o, &rounds) && + dec_loop_ssse3_inner(s, o, &rounds)) { + continue; + } + break; + } + if (rounds >= 2) { + if (dec_loop_ssse3_inner(s, o, &rounds) && + dec_loop_ssse3_inner(s, o, &rounds)) { + continue; + } + break; + } + dec_loop_ssse3_inner(s, o, &rounds); + break; + + } while (rounds > 0); + + // Adjust for any rounds that were skipped: + *slen += rounds * 16; + *olen -= rounds * 12; +} |