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Copy pathnbytes.cpp
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239 lines (204 loc) · 7.83 KB
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#include "nbytes.h"
#include <cmath>
#include <cstddef>
#include <string.h>
namespace nbytes {
// ============================================================================
// Byte Swapping
namespace {
// These are defined by <sys/byteorder.h> or <netinet/in.h> on some systems.
// To avoid warnings, undefine them before redefining them.
#ifdef BSWAP_2
#undef BSWAP_2
#endif
#ifdef BSWAP_4
#undef BSWAP_4
#endif
#ifdef BSWAP_8
#undef BSWAP_8
#endif
#if defined(_MSC_VER)
#include <intrin.h>
#define BSWAP_2(x) _byteswap_ushort(x)
#define BSWAP_4(x) _byteswap_ulong(x)
#define BSWAP_8(x) _byteswap_uint64(x)
#else
#define BSWAP_2(x) ((x) << 8) | ((x) >> 8)
#define BSWAP_4(x) \
(((x) & 0xFF) << 24) | (((x) & 0xFF00) << 8) | (((x) >> 8) & 0xFF00) | \
(((x) >> 24) & 0xFF)
#define BSWAP_8(x) \
(((x) & 0xFF00000000000000ull) >> 56) | \
(((x) & 0x00FF000000000000ull) >> 40) | \
(((x) & 0x0000FF0000000000ull) >> 24) | \
(((x) & 0x000000FF00000000ull) >> 8) | \
(((x) & 0x00000000FF000000ull) << 8) | \
(((x) & 0x0000000000FF0000ull) << 24) | \
(((x) & 0x000000000000FF00ull) << 40) | \
(((x) & 0x00000000000000FFull) << 56)
#endif
} // namespace
bool SwapBytes16(char *data, size_t nbytes) {
if (nbytes % sizeof(uint16_t) != 0) return false;
#if defined(_MSC_VER)
if (AlignUp(data, sizeof(uint16_t)) == data) {
// MSVC has no strict aliasing, and is able to highly optimize this case.
uint16_t *data16 = reinterpret_cast<uint16_t *>(data);
size_t len16 = nbytes / sizeof(uint16_t);
for (size_t i = 0; i < len16; i++) {
data16[i] = BSWAP_2(data16[i]);
}
return true;
}
#endif
uint16_t temp;
for (size_t i = 0; i < nbytes; i += sizeof(temp)) {
memcpy(&temp, &data[i], sizeof(temp));
temp = BSWAP_2(temp);
memcpy(&data[i], &temp, sizeof(temp));
}
return true;
}
bool SwapBytes32(char *data, size_t nbytes) {
if (nbytes % sizeof(uint32_t) != 0) return false;
#if defined(_MSC_VER)
// MSVC has no strict aliasing, and is able to highly optimize this case.
if (AlignUp(data, sizeof(uint32_t)) == data) {
uint32_t *data32 = reinterpret_cast<uint32_t *>(data);
size_t len32 = nbytes / sizeof(uint32_t);
for (size_t i = 0; i < len32; i++) {
data32[i] = BSWAP_4(data32[i]);
}
return true;
}
#endif
uint32_t temp;
for (size_t i = 0; i < nbytes; i += sizeof(temp)) {
memcpy(&temp, &data[i], sizeof(temp));
temp = BSWAP_4(temp);
memcpy(&data[i], &temp, sizeof(temp));
}
return true;
}
bool SwapBytes64(char *data, size_t nbytes) {
if (nbytes % sizeof(uint64_t) != 0) return false;
#if defined(_MSC_VER)
if (AlignUp(data, sizeof(uint64_t)) == data) {
// MSVC has no strict aliasing, and is able to highly optimize this case.
uint64_t *data64 = reinterpret_cast<uint64_t *>(data);
size_t len64 = nbytes / sizeof(uint64_t);
for (size_t i = 0; i < len64; i++) {
data64[i] = BSWAP_8(data64[i]);
}
return true;
}
#endif
uint64_t temp;
for (size_t i = 0; i < nbytes; i += sizeof(temp)) {
memcpy(&temp, &data[i], sizeof(temp));
temp = BSWAP_8(temp);
memcpy(&data[i], &temp, sizeof(temp));
}
return true;
}
// ============================================================================
// Base64 (legacy)
// supports regular and URL-safe base64
const int8_t unbase64_table[256] = {
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -1, -1, -2, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, 62, -1, 62, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60,
61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1,
63, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42,
43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1};
// ============================================================================
// Hex
const int8_t unhex_table[256] = {
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8,
9, -1, -1, -1, -1, -1, -1, -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1};
inline constexpr char nibble(uint8_t x) {
uint8_t add = (x >= 10) ? ('a' - 10) : '0';
return x + add;
}
size_t HexEncode(const char *src, size_t slen, char *dst, size_t dlen) {
// We know how much we'll write, just make sure that there's space.
NBYTES_ASSERT_TRUE(dlen >= MultiplyWithOverflowCheck<size_t>(slen, 2u) &&
"not enough space provided for hex encode");
dlen = slen * 2;
for (size_t i = 0, k = 0; k < dlen; i += 1, k += 2) {
uint8_t val = static_cast<uint8_t>(src[i]);
dst[k + 0] = nibble(val >> 4);
dst[k + 1] = nibble(val & 15);
}
return dlen;
}
std::string HexEncode(const char *src, size_t slen) {
size_t dlen = slen * 2;
std::string dst(dlen, '\0');
HexEncode(src, slen, dst.data(), dlen);
return dst;
}
// ============================================================================
void ForceAsciiSlow(const char *src, char *dst, size_t len) {
for (size_t i = 0; i < len; ++i) {
dst[i] = src[i] & 0x7f;
}
}
void ForceAscii(const char *src, char *dst, size_t len) {
if (len < 16) {
ForceAsciiSlow(src, dst, len);
return;
}
const unsigned bytes_per_word = sizeof(uintptr_t);
const unsigned align_mask = bytes_per_word - 1;
const unsigned src_unalign = reinterpret_cast<uintptr_t>(src) & align_mask;
const unsigned dst_unalign = reinterpret_cast<uintptr_t>(dst) & align_mask;
if (src_unalign > 0) {
if (src_unalign == dst_unalign) {
const unsigned unalign = bytes_per_word - src_unalign;
ForceAsciiSlow(src, dst, unalign);
src += unalign;
dst += unalign;
len -= unalign;
} else {
ForceAsciiSlow(src, dst, len);
return;
}
}
#if defined(_WIN64) || defined(_LP64)
const uintptr_t mask = ~0x8080808080808080ll;
#else
const uintptr_t mask = ~0x80808080l;
#endif
const uintptr_t *srcw = reinterpret_cast<const uintptr_t *>(src);
uintptr_t *dstw = reinterpret_cast<uintptr_t *>(dst);
for (size_t i = 0, n = len / bytes_per_word; i < n; ++i) {
dstw[i] = srcw[i] & mask;
}
const unsigned remainder = len & align_mask;
if (remainder > 0) {
const size_t offset = len - remainder;
ForceAsciiSlow(src + offset, dst + offset, remainder);
}
}
} // namespace nbytes