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https://github.com/matrix-construct/construct
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ircd::b64: Add parallel SIMD base64 decoder.
This commit is contained in:
Jason Volk
parent
d51082ef17
commit
f3f441ac19
3 changed files with 123 additions and 24 deletions
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@ -80,5 +80,5 @@ constexpr size_t
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ircd::b64::decode_size(const size_t &in)
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noexcept
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{
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return (in * 0.75) + 1; //XXX: constexpr ceil()
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return in * (3.0 / 4.0);
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}
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@ -205,7 +205,6 @@ libircd_la_SOURCES += ircd.cc
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# Specific unit configurations
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#
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b64.lo: AM_CPPFLAGS := @BOOST_CPPFLAGS@ ${AM_CPPFLAGS}
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client.lo: AM_CPPFLAGS := ${ASIO_UNIT_CPPFLAGS} ${AM_CPPFLAGS}
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ctx_x86_64.lo: AM_CPPFLAGS := -I$(top_srcdir)/include
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ctx.lo: AM_CPPFLAGS := ${ASIO_UNIT_CPPFLAGS} ${AM_CPPFLAGS}
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144
ircd/b64.cc
144
ircd/b64.cc
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@ -8,9 +8,6 @@
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// copyright notice and this permission notice is present in all copies. The
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// full license for this software is available in the LICENSE file.
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#include <boost/archive/iterators/binary_from_base64.hpp>
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#include <boost/archive/iterators/transform_width.hpp>
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#pragma GCC visibility push(internal)
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namespace ircd::b64
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{
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@ -22,7 +19,15 @@ namespace ircd::b64
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[[gnu::aligned(64)]]
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extern const u8
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encode_permute_tab[64],
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encode_shift_ctrl[64];
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encode_shift_ctrl[64],
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decode_permute_tab[64],
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decode_permute_tab_le[64];
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[[gnu::aligned(64)]]
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extern const i32
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decode_dictionary[256];
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static u8x64 decode_block(const u8x64 in) noexcept;
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template<const u8 (&dict)[64]>
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static u8x64 encode_block(const u8x64 in) noexcept;
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@ -56,8 +61,47 @@ ircd::b64::dict_rfc4648
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'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_',
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};
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decltype(ircd::b64::decode_dictionary)
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ircd::b64::decode_dictionary
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{
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // 7
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // 15
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // 23
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // 31
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // 39
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0x00, 0x00, 0x00, 62, 63, 62, 0x00, 63, // 47
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52, 53, 54, 55, 56, 57, 58, 59, // 55
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60, 61, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // 63
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0x00, 0, 1, 2, 3, 4, 5, 6, // 71
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7, 8, 9, 10, 11, 12, 13, 14, // 79
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15, 16, 17, 18, 19, 20, 21, 22, // 87
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23, 24, 25, 0x00, 0x00, 0x00, 0x00, 63, // 95
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0x00, 26, 27, 28, 29, 30, 31, 32, // 103
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33, 34, 35, 36, 37, 38, 39, 40, // 111
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41, 42, 43, 44, 45, 46, 47, 48, // 119
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49, 50, 51, 0x00, 0x00, 0x00, 0x00, 0x00, // 127
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};
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decltype(ircd::b64::decode_permute_tab)
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ircd::b64::decode_permute_tab
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{
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6, 0, 1, 2, 9, 10, 4, 5, 12, 13, 14, 8, 22, 16, 17, 18,
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25, 26, 20, 21, 28, 29, 30, 24, 38, 32, 33, 34, 41, 42, 36, 37,
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44, 45, 46, 40, 54, 48, 49, 50, 57, 58, 52, 53, 60, 61, 62, 56,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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};
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/// byte-order swapped for each 32-bit word from above
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decltype(ircd::b64::decode_permute_tab_le)
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ircd::b64::decode_permute_tab_le
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{
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2, 1, 0, 6, 5, 4, 10, 9, 8, 14, 13, 12, 18, 17, 16, 22,
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21, 20, 26, 25, 24, 30, 29, 28, 34, 33, 32, 38, 37, 36, 42, 41,
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40, 46, 45, 44, 50, 49, 48, 54, 53, 52, 58, 57, 56, 62, 61, 60,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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};
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/// For vpermb
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/// From arXiv:1910.05109v1 [Mula, Lemire] 2 Oct 2019
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decltype(ircd::b64::encode_permute_tab)
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ircd::b64::encode_permute_tab
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{
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@ -72,7 +116,6 @@ ircd::b64::encode_permute_tab
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};
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/// For vpmultishiftqb
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/// From arXiv:1910.05109v1 [Mula, Lemire] 2 Oct 2019
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decltype(ircd::b64::encode_shift_ctrl)
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ircd::b64::encode_shift_ctrl
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{
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@ -226,28 +269,85 @@ ircd::const_buffer
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ircd::b64::decode(const mutable_buffer &out,
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const string_view &in)
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{
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namespace iterators = boost::archive::iterators;
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using b64bf = iterators::binary_from_base64<const char *>;
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using transform = iterators::transform_width<b64bf, 8, 6>;
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const auto pads
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const size_t out_len
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{
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endswith_count(in, b64::pad)
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std::min(decode_size(in), size(out))
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};
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const auto e
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size_t i(0), j(0);
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for(; i + 1 <= (size(in) / 64) && i + 1 <= (out_len / 48); ++i)
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{
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std::copy(transform(begin(in)), transform(begin(in) + size(in) - pads), begin(out))
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};
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// Destination is indexed at 48 byte stride
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const auto di
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{
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reinterpret_cast<u512x1_u *__restrict__>(data(out) + (i * 48))
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};
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const auto len
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{
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std::distance(begin(out), e)
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};
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// Source is indexed at 64 byte stride
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const auto si
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{
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reinterpret_cast<const u512x1_u *__restrict__>(data(in) + (i * 64))
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};
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assert(size_t(len) <= size(out));
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return const_buffer
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*di = decode_block(*si);
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}
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for(; i * 64 < size(in) && i * 48 < out_len; ++i)
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{
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data(out), size_t(len)
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u8x64 block {0};
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for(j = 0; j < 64 && i * 64 + j < size(in); ++j)
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block[j] = in[i * 64 + j];
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block = decode_block(block);
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for(j = 0; j < 48 && i * 48 + j < out_len; ++j)
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out[i * 48 + j] = block[j];
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}
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return string_view
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{
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data(out), out_len
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};
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}
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/// Decode 64 base64 characters into a 48 byte result. The last 48 bytes of
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/// the returned vector are undefined for the caller.
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ircd::u8x64
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ircd::b64::decode_block(const u8x64 in)
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noexcept
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{
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size_t i, j;
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i32x16 zz[4];
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for(i = 0; i < 4; ++i)
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for(j = 0; j < 16; ++j)
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zz[i][j] = decode_dictionary[in[i * 16 + j]];
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u8x64 z;
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for(i = 0; i < 4; ++i)
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for(j = 0; j < 16; ++j)
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z[i * 16 + j] = zz[i][j];
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u16x32 al, ah;
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for(i = 0, j = 0; i < 32; ++i)
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ah[i] = z[j++],
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al[i] = z[j++];
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u16x32 a;
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for(i = 0; i < 32; ++i)
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a[i] = ah[i] * 64 + al[i];
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u32x16 bl, bh;
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for(i = 0, j = 0; i < 16; ++i)
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bh[i] = a[j++],
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bl[i] = a[j++];
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u32x16 b;
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for(i = 0; i < 16; ++i)
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b[i] = bh[i] * 4096 + bl[i];
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u8x64 d, c(b);
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for(i = 0; i < 64; ++i)
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d[i] = c[decode_permute_tab_le[i]];
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return d;
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}
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