summaryrefslogtreecommitdiffstats
path: root/src/third-party/base64/lib/arch/ssse3/dec_loop.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/third-party/base64/lib/arch/ssse3/dec_loop.c')
-rw-r--r--src/third-party/base64/lib/arch/ssse3/dec_loop.c173
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;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-05-24 12:16:11 +0000