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duckstation/dep/rapidyaml/src/c4/base64.cpp

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#include "c4/base64.hpp"
#ifdef __clang__
# pragma clang diagnostic push
# pragma clang diagnostic ignored "-Wchar-subscripts" // array subscript is of type 'char'
# pragma clang diagnostic ignored "-Wold-style-cast"
#elif defined(__GNUC__)
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Wchar-subscripts"
# pragma GCC diagnostic ignored "-Wtype-limits"
# pragma GCC diagnostic ignored "-Wold-style-cast"
#endif
namespace c4 {
namespace detail {
constexpr static const char base64_sextet_to_char_[64] = {
/* 0/ 65*/ 'A', /* 1/ 66*/ 'B', /* 2/ 67*/ 'C', /* 3/ 68*/ 'D',
/* 4/ 69*/ 'E', /* 5/ 70*/ 'F', /* 6/ 71*/ 'G', /* 7/ 72*/ 'H',
/* 8/ 73*/ 'I', /* 9/ 74*/ 'J', /*10/ 75*/ 'K', /*11/ 74*/ 'L',
/*12/ 77*/ 'M', /*13/ 78*/ 'N', /*14/ 79*/ 'O', /*15/ 78*/ 'P',
/*16/ 81*/ 'Q', /*17/ 82*/ 'R', /*18/ 83*/ 'S', /*19/ 82*/ 'T',
/*20/ 85*/ 'U', /*21/ 86*/ 'V', /*22/ 87*/ 'W', /*23/ 88*/ 'X',
/*24/ 89*/ 'Y', /*25/ 90*/ 'Z', /*26/ 97*/ 'a', /*27/ 98*/ 'b',
/*28/ 99*/ 'c', /*29/100*/ 'd', /*30/101*/ 'e', /*31/102*/ 'f',
/*32/103*/ 'g', /*33/104*/ 'h', /*34/105*/ 'i', /*35/106*/ 'j',
/*36/107*/ 'k', /*37/108*/ 'l', /*38/109*/ 'm', /*39/110*/ 'n',
/*40/111*/ 'o', /*41/112*/ 'p', /*42/113*/ 'q', /*43/114*/ 'r',
/*44/115*/ 's', /*45/116*/ 't', /*46/117*/ 'u', /*47/118*/ 'v',
/*48/119*/ 'w', /*49/120*/ 'x', /*50/121*/ 'y', /*51/122*/ 'z',
/*52/ 48*/ '0', /*53/ 49*/ '1', /*54/ 50*/ '2', /*55/ 51*/ '3',
/*56/ 52*/ '4', /*57/ 53*/ '5', /*58/ 54*/ '6', /*59/ 55*/ '7',
/*60/ 56*/ '8', /*61/ 57*/ '9', /*62/ 43*/ '+', /*63/ 47*/ '/',
};
// https://www.cs.cmu.edu/~pattis/15-1XX/common/handouts/ascii.html
constexpr static const char base64_char_to_sextet_[128] = {
#define __ char(-1) // undefined below
/* 0 NUL*/ __, /* 1 SOH*/ __, /* 2 STX*/ __, /* 3 ETX*/ __,
/* 4 EOT*/ __, /* 5 ENQ*/ __, /* 6 ACK*/ __, /* 7 BEL*/ __,
/* 8 BS */ __, /* 9 TAB*/ __, /* 10 LF */ __, /* 11 VT */ __,
/* 12 FF */ __, /* 13 CR */ __, /* 14 SO */ __, /* 15 SI */ __,
/* 16 DLE*/ __, /* 17 DC1*/ __, /* 18 DC2*/ __, /* 19 DC3*/ __,
/* 20 DC4*/ __, /* 21 NAK*/ __, /* 22 SYN*/ __, /* 23 ETB*/ __,
/* 24 CAN*/ __, /* 25 EM */ __, /* 26 SUB*/ __, /* 27 ESC*/ __,
/* 28 FS */ __, /* 29 GS */ __, /* 30 RS */ __, /* 31 US */ __,
/* 32 SPC*/ __, /* 33 ! */ __, /* 34 " */ __, /* 35 # */ __,
/* 36 $ */ __, /* 37 % */ __, /* 38 & */ __, /* 39 ' */ __,
/* 40 ( */ __, /* 41 ) */ __, /* 42 * */ __, /* 43 + */ 62,
/* 44 , */ __, /* 45 - */ __, /* 46 . */ __, /* 47 / */ 63,
/* 48 0 */ 52, /* 49 1 */ 53, /* 50 2 */ 54, /* 51 3 */ 55,
/* 52 4 */ 56, /* 53 5 */ 57, /* 54 6 */ 58, /* 55 7 */ 59,
/* 56 8 */ 60, /* 57 9 */ 61, /* 58 : */ __, /* 59 ; */ __,
/* 60 < */ __, /* 61 = */ __, /* 62 > */ __, /* 63 ? */ __,
/* 64 @ */ __, /* 65 A */ 0, /* 66 B */ 1, /* 67 C */ 2,
/* 68 D */ 3, /* 69 E */ 4, /* 70 F */ 5, /* 71 G */ 6,
/* 72 H */ 7, /* 73 I */ 8, /* 74 J */ 9, /* 75 K */ 10,
/* 76 L */ 11, /* 77 M */ 12, /* 78 N */ 13, /* 79 O */ 14,
/* 80 P */ 15, /* 81 Q */ 16, /* 82 R */ 17, /* 83 S */ 18,
/* 84 T */ 19, /* 85 U */ 20, /* 86 V */ 21, /* 87 W */ 22,
/* 88 X */ 23, /* 89 Y */ 24, /* 90 Z */ 25, /* 91 [ */ __,
/* 92 \ */ __, /* 93 ] */ __, /* 94 ^ */ __, /* 95 _ */ __,
/* 96 ` */ __, /* 97 a */ 26, /* 98 b */ 27, /* 99 c */ 28,
/*100 d */ 29, /*101 e */ 30, /*102 f */ 31, /*103 g */ 32,
/*104 h */ 33, /*105 i */ 34, /*106 j */ 35, /*107 k */ 36,
/*108 l */ 37, /*109 m */ 38, /*110 n */ 39, /*111 o */ 40,
/*112 p */ 41, /*113 q */ 42, /*114 r */ 43, /*115 s */ 44,
/*116 t */ 45, /*117 u */ 46, /*118 v */ 47, /*119 w */ 48,
/*120 x */ 49, /*121 y */ 50, /*122 z */ 51, /*123 { */ __,
/*124 | */ __, /*125 } */ __, /*126 ~ */ __, /*127 DEL*/ __,
#undef __
};
#ifndef NDEBUG
void base64_test_tables()
{
for(size_t i = 0; i < C4_COUNTOF(detail::base64_sextet_to_char_); ++i)
{
char s2c = base64_sextet_to_char_[i];
char c2s = base64_char_to_sextet_[(int)s2c];
C4_CHECK((size_t)c2s == i);
}
for(size_t i = 0; i < C4_COUNTOF(detail::base64_char_to_sextet_); ++i)
{
char c2s = base64_char_to_sextet_[i];
if(c2s == char(-1))
continue;
char s2c = base64_sextet_to_char_[(int)c2s];
C4_CHECK((size_t)s2c == i);
}
}
#endif
} // namespace detail
bool base64_valid(csubstr encoded)
{
if(encoded.len & 3u) // (encoded.len % 4u)
return false;
for(const char c : encoded)
{
if(c < 0/* || c >= 128*/)
return false;
if(c == '=')
continue;
if(detail::base64_char_to_sextet_[c] == char(-1))
return false;
}
return true;
}
size_t base64_encode(substr buf, cblob data)
{
#define c4append_(c) { if(pos < buf.len) { buf.str[pos] = (c); } ++pos; }
#define c4append_idx_(char_idx) \
{\
C4_XASSERT((char_idx) < sizeof(detail::base64_sextet_to_char_));\
c4append_(detail::base64_sextet_to_char_[(char_idx)]);\
}
size_t rem, pos = 0;
constexpr const uint32_t sextet_mask = uint32_t(1 << 6) - 1;
const unsigned char *C4_RESTRICT d = (const unsigned char *) data.buf; // cast to unsigned to avoid wrapping high-bits
for(rem = data.len; rem >= 3; rem -= 3, d += 3)
{
const uint32_t val = ((uint32_t(d[0]) << 16) | (uint32_t(d[1]) << 8) | (uint32_t(d[2])));
c4append_idx_((val >> 18) & sextet_mask);
c4append_idx_((val >> 12) & sextet_mask);
c4append_idx_((val >> 6) & sextet_mask);
c4append_idx_((val ) & sextet_mask);
}
C4_ASSERT(rem < 3);
if(rem == 2)
{
const uint32_t val = ((uint32_t(d[0]) << 16) | (uint32_t(d[1]) << 8));
c4append_idx_((val >> 18) & sextet_mask);
c4append_idx_((val >> 12) & sextet_mask);
c4append_idx_((val >> 6) & sextet_mask);
c4append_('=');
}
else if(rem == 1)
{
const uint32_t val = ((uint32_t(d[0]) << 16));
c4append_idx_((val >> 18) & sextet_mask);
c4append_idx_((val >> 12) & sextet_mask);
c4append_('=');
c4append_('=');
}
return pos;
#undef c4append_
#undef c4append_idx_
}
size_t base64_decode(csubstr encoded, blob data)
{
#define c4append_(c) { if(wpos < data.len) { data.buf[wpos] = static_cast<c4::byte>(c); } ++wpos; }
#define c4appendval_(c, shift)\
{\
C4_XASSERT(c >= 0);\
C4_XASSERT(size_t(c) < sizeof(detail::base64_char_to_sextet_));\
val |= static_cast<uint32_t>(detail::base64_char_to_sextet_[(c)]) << ((shift) * 6);\
}
C4_ASSERT(base64_valid(encoded));
C4_CHECK((encoded.len & 3u) == 0);
size_t wpos = 0; // the write position
const char *C4_RESTRICT d = encoded.str;
constexpr const uint32_t full_byte = 0xff;
// process every quartet of input 6 bits --> triplet of output bytes
for(size_t rpos = 0; rpos < encoded.len; rpos += 4, d += 4)
{
if(d[2] == '=' || d[3] == '=') // skip the last quartet if it is padded
{
C4_ASSERT(d + 4 == encoded.str + encoded.len);
break;
}
uint32_t val = 0;
c4appendval_(d[3], 0);
c4appendval_(d[2], 1);
c4appendval_(d[1], 2);
c4appendval_(d[0], 3);
c4append_((val >> (2 * 8)) & full_byte);
c4append_((val >> (1 * 8)) & full_byte);
c4append_((val ) & full_byte);
}
// deal with the last quartet when it is padded
if(d == encoded.str + encoded.len)
return wpos;
if(d[2] == '=') // 2 padding chars
{
C4_ASSERT(d + 4 == encoded.str + encoded.len);
C4_ASSERT(d[3] == '=');
uint32_t val = 0;
c4appendval_(d[1], 2);
c4appendval_(d[0], 3);
c4append_((val >> (2 * 8)) & full_byte);
}
else if(d[3] == '=') // 1 padding char
{
C4_ASSERT(d + 4 == encoded.str + encoded.len);
uint32_t val = 0;
c4appendval_(d[2], 1);
c4appendval_(d[1], 2);
c4appendval_(d[0], 3);
c4append_((val >> (2 * 8)) & full_byte);
c4append_((val >> (1 * 8)) & full_byte);
}
return wpos;
#undef c4append_
#undef c4appendval_
}
} // namespace c4
#ifdef __clang__
# pragma clang diagnostic pop
#elif defined(__GNUC__)
# pragma GCC diagnostic pop
#endif
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