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#include <stdint.h>
#include <stddef.h>
#include <stdlib.h>
#include "libbase64.h"
#include "codecs.h"
#ifdef __AVX2__
#include <immintrin.h>
#define CMPGT(s,n) _mm256_cmpgt_epi8((s), _mm256_set1_epi8(n))
#define CMPEQ(s,n) _mm256_cmpeq_epi8((s), _mm256_set1_epi8(n))
#define REPLACE(s,n) _mm256_and_si256((s), _mm256_set1_epi8(n))
#define RANGE(s,a,b) _mm256_andnot_si256(CMPGT((s), (b)), CMPGT((s), (a) - 1))
static inline __m256i
_mm256_bswap_epi32 (const __m256i in)
{
// _mm256_shuffle_epi8() works on two 128-bit lanes separately:
return _mm256_shuffle_epi8(in, _mm256_setr_epi8(
3, 2, 1, 0,
7, 6, 5, 4,
11, 10, 9, 8,
15, 14, 13, 12,
3, 2, 1, 0,
7, 6, 5, 4,
11, 10, 9, 8,
15, 14, 13, 12));
}
static inline __m256i
enc_reshuffle (__m256i in)
{
// Spread out 32-bit words over both halves of the input register:
in = _mm256_permutevar8x32_epi32(in, _mm256_setr_epi32(
0, 1, 2, -1,
3, 4, 5, -1));
// Slice into 32-bit chunks and operate on all chunks in parallel.
// All processing is done within the 32-bit chunk. First, shuffle:
// before: [eeeeeeff|ccdddddd|bbbbcccc|aaaaaabb]
// after: [00000000|aaaaaabb|bbbbcccc|ccdddddd]
in = _mm256_shuffle_epi8(in, _mm256_set_epi8(
-1, 9, 10, 11,
-1, 6, 7, 8,
-1, 3, 4, 5,
-1, 0, 1, 2,
-1, 9, 10, 11,
-1, 6, 7, 8,
-1, 3, 4, 5,
-1, 0, 1, 2));
// cd = [00000000|00000000|0000cccc|ccdddddd]
const __m256i cd = _mm256_and_si256(in, _mm256_set1_epi32(0x00000FFF));
// ab = [0000aaaa|aabbbbbb|00000000|00000000]
const __m256i ab = _mm256_and_si256(_mm256_slli_epi32(in, 4), _mm256_set1_epi32(0x0FFF0000));
// merged = [0000aaaa|aabbbbbb|0000cccc|ccdddddd]
const __m256i merged = _mm256_or_si256(ab, cd);
// bd = [00000000|00bbbbbb|00000000|00dddddd]
const __m256i bd = _mm256_and_si256(merged, _mm256_set1_epi32(0x003F003F));
// ac = [00aaaaaa|00000000|00cccccc|00000000]
const __m256i ac = _mm256_and_si256(_mm256_slli_epi32(merged, 2), _mm256_set1_epi32(0x3F003F00));
// indices = [00aaaaaa|00bbbbbb|00cccccc|00dddddd]
const __m256i indices = _mm256_or_si256(ac, bd);
// return = [00dddddd|00cccccc|00bbbbbb|00aaaaaa]
return _mm256_bswap_epi32(indices);
}
static inline __m256i
enc_translate (const __m256i in)
{
// Translate values 0..63 to the Base64 alphabet. There are five sets:
// # From To Abs Delta Characters
// 0 [0..25] [65..90] +65 +65 ABCDEFGHIJKLMNOPQRSTUVWXYZ
// 1 [26..51] [97..122] +71 +6 abcdefghijklmnopqrstuvwxyz
// 2 [52..61] [48..57] -4 -75 0123456789
// 3 [62] [43] -19 -15 +
// 4 [63] [47] -16 +3 /
// Create cumulative masks for characters in sets [1,2,3,4], [2,3,4],
// [3,4], and [4]:
const __m256i mask1 = CMPGT(in, 25);
const __m256i mask2 = CMPGT(in, 51);
const __m256i mask3 = CMPGT(in, 61);
const __m256i mask4 = CMPEQ(in, 63);
// All characters are at least in cumulative set 0, so add 'A':
__m256i out = _mm256_add_epi8(in, _mm256_set1_epi8(65));
// For inputs which are also in any of the other cumulative sets,
// add delta values against the previous set(s) to correct the shift:
out = _mm256_add_epi8(out, REPLACE(mask1, 6));
out = _mm256_sub_epi8(out, REPLACE(mask2, 75));
out = _mm256_sub_epi8(out, REPLACE(mask3, 15));
out = _mm256_add_epi8(out, REPLACE(mask4, 3));
return out;
}
static inline __m256i
dec_reshuffle (__m256i in)
{
// Shuffle bytes to 32-bit bigendian:
in = _mm256_bswap_epi32(in);
// Mask in a single byte per shift:
__m256i mask = _mm256_set1_epi32(0x3F000000);
// Pack bytes together:
__m256i out = _mm256_slli_epi32(_mm256_and_si256(in, mask), 2);
mask = _mm256_srli_epi32(mask, 8);
out = _mm256_or_si256(out, _mm256_slli_epi32(_mm256_and_si256(in, mask), 4));
mask = _mm256_srli_epi32(mask, 8);
out = _mm256_or_si256(out, _mm256_slli_epi32(_mm256_and_si256(in, mask), 6));
mask = _mm256_srli_epi32(mask, 8);
out = _mm256_or_si256(out, _mm256_slli_epi32(_mm256_and_si256(in, mask), 8));
// Pack bytes together within 32-bit words, discarding words 3 and 7:
out = _mm256_shuffle_epi8(out, _mm256_setr_epi8(
3, 2, 1,
7, 6, 5,
11, 10, 9,
15, 14, 13,
-1, -1, -1, -1,
3, 2, 1,
7, 6, 5,
11, 10, 9,
15, 14, 13,
-1, -1, -1, -1));
// Pack 32-bit words together, squashing empty words 3 and 7:
return _mm256_permutevar8x32_epi32(out, _mm256_setr_epi32(
0, 1, 2, 4, 5, 6, -1, -1));
}
#endif // __AVX2__
void
avx2_base64_stream_encode
( struct avx2_base64_state *state
, const char *src
, size_t srclen
, char *out
, size_t *outlen
)
{
#if defined(__AVX2__)
#include "enc_head.c"
#include "enc_avx2.c"
#include "enc_tail.c"
#else
(void)state;
(void)src;
(void)srclen;
(void)out;
(void)outlen;
abort();
#endif
}
int
avx2_base64_stream_decode
( struct avx2_base64_state *state
, const char *src
, size_t srclen
, char *out
, size_t *outlen
)
{
#if defined(__AVX2__)
#include "dec_head.c"
#include "dec_avx2.c"
#include "dec_tail.c"
#else
(void)state;
(void)src;
(void)srclen;
(void)out;
(void)outlen;
abort();
#endif
}
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