aboutsummaryrefslogtreecommitdiff
path: root/util/coding.cc
diff options
context:
space:
mode:
Diffstat (limited to 'util/coding.cc')
-rw-r--r--util/coding.cc194
1 files changed, 194 insertions, 0 deletions
diff --git a/util/coding.cc b/util/coding.cc
new file mode 100644
index 0000000000..21e3186d5d
--- /dev/null
+++ b/util/coding.cc
@@ -0,0 +1,194 @@
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#include "util/coding.h"
+
+namespace leveldb {
+
+void EncodeFixed32(char* buf, uint32_t value) {
+ if (port::kLittleEndian) {
+ memcpy(buf, &value, sizeof(value));
+ } else {
+ buf[0] = value & 0xff;
+ buf[1] = (value >> 8) & 0xff;
+ buf[2] = (value >> 16) & 0xff;
+ buf[3] = (value >> 24) & 0xff;
+ }
+}
+
+void EncodeFixed64(char* buf, uint64_t value) {
+ if (port::kLittleEndian) {
+ memcpy(buf, &value, sizeof(value));
+ } else {
+ buf[0] = value & 0xff;
+ buf[1] = (value >> 8) & 0xff;
+ buf[2] = (value >> 16) & 0xff;
+ buf[3] = (value >> 24) & 0xff;
+ buf[4] = (value >> 32) & 0xff;
+ buf[5] = (value >> 40) & 0xff;
+ buf[6] = (value >> 48) & 0xff;
+ buf[7] = (value >> 56) & 0xff;
+ }
+}
+
+void PutFixed32(std::string* dst, uint32_t value) {
+ char buf[sizeof(value)];
+ EncodeFixed32(buf, value);
+ dst->append(buf, sizeof(buf));
+}
+
+void PutFixed64(std::string* dst, uint64_t value) {
+ char buf[sizeof(value)];
+ EncodeFixed64(buf, value);
+ dst->append(buf, sizeof(buf));
+}
+
+char* EncodeVarint32(char* dst, uint32_t v) {
+ // Operate on characters as unsigneds
+ unsigned char* ptr = reinterpret_cast<unsigned char*>(dst);
+ static const int B = 128;
+ if (v < (1<<7)) {
+ *(ptr++) = v;
+ } else if (v < (1<<14)) {
+ *(ptr++) = v | B;
+ *(ptr++) = v>>7;
+ } else if (v < (1<<21)) {
+ *(ptr++) = v | B;
+ *(ptr++) = (v>>7) | B;
+ *(ptr++) = v>>14;
+ } else if (v < (1<<28)) {
+ *(ptr++) = v | B;
+ *(ptr++) = (v>>7) | B;
+ *(ptr++) = (v>>14) | B;
+ *(ptr++) = v>>21;
+ } else {
+ *(ptr++) = v | B;
+ *(ptr++) = (v>>7) | B;
+ *(ptr++) = (v>>14) | B;
+ *(ptr++) = (v>>21) | B;
+ *(ptr++) = v>>28;
+ }
+ return reinterpret_cast<char*>(ptr);
+}
+
+void PutVarint32(std::string* dst, uint32_t v) {
+ char buf[5];
+ char* ptr = EncodeVarint32(buf, v);
+ dst->append(buf, ptr - buf);
+}
+
+char* EncodeVarint64(char* dst, uint64_t v) {
+ static const int B = 128;
+ unsigned char* ptr = reinterpret_cast<unsigned char*>(dst);
+ while (v >= B) {
+ *(ptr++) = (v & (B-1)) | B;
+ v >>= 7;
+ }
+ *(ptr++) = static_cast<unsigned char>(v);
+ return reinterpret_cast<char*>(ptr);
+}
+
+void PutVarint64(std::string* dst, uint64_t v) {
+ char buf[10];
+ char* ptr = EncodeVarint64(buf, v);
+ dst->append(buf, ptr - buf);
+}
+
+void PutLengthPrefixedSlice(std::string* dst, const Slice& value) {
+ PutVarint32(dst, value.size());
+ dst->append(value.data(), value.size());
+}
+
+int VarintLength(uint64_t v) {
+ int len = 1;
+ while (v >= 128) {
+ v >>= 7;
+ len++;
+ }
+ return len;
+}
+
+const char* GetVarint32PtrFallback(const char* p,
+ const char* limit,
+ uint32_t* value) {
+ uint32_t result = 0;
+ for (uint32_t shift = 0; shift <= 28 && p < limit; shift += 7) {
+ uint32_t byte = *(reinterpret_cast<const unsigned char*>(p));
+ p++;
+ if (byte & 128) {
+ // More bytes are present
+ result |= ((byte & 127) << shift);
+ } else {
+ result |= (byte << shift);
+ *value = result;
+ return reinterpret_cast<const char*>(p);
+ }
+ }
+ return NULL;
+}
+
+bool GetVarint32(Slice* input, uint32_t* value) {
+ const char* p = input->data();
+ const char* limit = p + input->size();
+ const char* q = GetVarint32Ptr(p, limit, value);
+ if (q == NULL) {
+ return false;
+ } else {
+ *input = Slice(q, limit - q);
+ return true;
+ }
+}
+
+const char* GetVarint64Ptr(const char* p, const char* limit, uint64_t* value) {
+ uint64_t result = 0;
+ for (uint32_t shift = 0; shift <= 63 && p < limit; shift += 7) {
+ uint64_t byte = *(reinterpret_cast<const unsigned char*>(p));
+ p++;
+ if (byte & 128) {
+ // More bytes are present
+ result |= ((byte & 127) << shift);
+ } else {
+ result |= (byte << shift);
+ *value = result;
+ return reinterpret_cast<const char*>(p);
+ }
+ }
+ return NULL;
+}
+
+bool GetVarint64(Slice* input, uint64_t* value) {
+ const char* p = input->data();
+ const char* limit = p + input->size();
+ const char* q = GetVarint64Ptr(p, limit, value);
+ if (q == NULL) {
+ return false;
+ } else {
+ *input = Slice(q, limit - q);
+ return true;
+ }
+}
+
+const char* GetLengthPrefixedSlice(const char* p, const char* limit,
+ Slice* result) {
+ uint32_t len;
+ p = GetVarint32Ptr(p, limit, &len);
+ if (p == NULL) return NULL;
+ if (p + len > limit) return NULL;
+ *result = Slice(p, len);
+ return p + len;
+}
+
+bool GetLengthPrefixedSlice(Slice* input, Slice* result) {
+ uint32_t len;
+ if (GetVarint32(input, &len) &&
+ input->size() >= len) {
+ *result = Slice(input->data(), len);
+ input->remove_prefix(len);
+ return true;
+ } else {
+ return false;
+ }
+}
+
+} // namespace leveldb