问题 1：如何破译函数名称，例如 _ZN21CircularBufferManager4readIlEEmPT_m ？我猜那些长函数名（即l、t、h、d）中“read”之后的第二个字符一定与类型有关。我使用无符号字符、无符号短、有符号长、双精度。
问题 2：在第 227 行，我看到 16 个分支。为什么是16？另一方面，第 222 行有 8 个分支，这对我来说很有意义，因为 2 个状态（真或假）乘以 4 个函数构成 8 个分支。
-: 216: template<typename Type>
function _ZN21CircularBufferManager4readIlEEmPT_m called 2 returned 100% blocks executed 63%
function _ZN21CircularBufferManager4readItEEmPT_m called 2 returned 100% blocks executed 50%
function _ZN21CircularBufferManager4readIhEEmPT_m called 10 returned 100% blocks executed 94%
function _ZN21CircularBufferManager4readIdEEmPT_m called 8 returned 100% blocks executed 94%
22: 217: uint32 read(Type* data, uint32 element_count)
-: 218: {
22: 219: uint32 size(sizeof(Type)*element_count);
-: 220:
22: 221: uint32 write_pos_alias(this->write_pos);
22: 222: if (this->read_pos > this->write_pos) {
branch 0 taken 0% (fallthrough)
branch 1 taken 100%
branch 2 taken 0% (fallthrough)
branch 3 taken 100%
branch 4 taken 20% (fallthrough)
branch 5 taken 80%
branch 6 taken 13% (fallthrough)
branch 7 taken 88%
3: 223: write_pos_alias += this->allocated_size;
-: 224: }
-: 225: assert(write_pos_alias >= this->read_pos);
22: 226: uint32 n(write_pos_alias - this->read_pos); // number of bytes to reach the write position
22: 227: if (n==0 && this->stored_count==0) // <=> buffer is empty
branch 0 taken 50% (fallthrough)
branch 1 taken 50%
branch 2 taken 100% (fallthrough)
branch 3 taken 0%
branch 4 taken 0% (fallthrough)
branch 5 taken 100%
branch 6 never executed
branch 7 never executed
branch 8 taken 30% (fallthrough)
branch 9 taken 70%
branch 10 taken 0% (fallthrough)
branch 11 taken 100%
branch 12 taken 38% (fallthrough)
branch 13 taken 63%
branch 14 taken 0% (fallthrough)
branch 15 taken 100%
-: 228: {
-: 229: // no data read
1: 230: return 0;
-: 231: }
21: 232: else if (0<n && n<size) // read is stopped before read_pos crosses over write_pos.
branch 0 taken 100% (fallthrough)
branch 1 taken 0%
branch 2 taken 0% (fallthrough)
branch 3 taken 100%
branch 4 taken 100% (fallthrough)
branch 5 taken 0%
branch 6 taken 0% (fallthrough)
branch 7 taken 100%
branch 8 taken 70% (fallthrough)
branch 9 taken 30%
branch 10 taken 14% (fallthrough)
branch 11 taken 86%
branch 12 taken 63% (fallthrough)
branch 13 taken 38%
branch 14 taken 20% (fallthrough)
branch 15 taken 80%
-: 233: {
2: 234: return read(reinterpret_cast<uint8*>(data), n); //less data than required.
call 0 never executed
call 1 never executed
call 2 returned 100%
call 3 returned 100%
-: 235: }
-: 236: // It is guaranteed here and below that read_pos never crosses-over write_pos.
-: 237:
19: 238: if (this->read_pos + size > this->allocated_size) // going beyond the end of buffer
branch 0 taken 0% (fallthrough)
branch 1 taken 100%
branch 2 taken 0% (fallthrough)
branch 3 taken 100%
branch 4 taken 11% (fallthrough)
branch 5 taken 89%
branch 6 taken 43% (fallthrough)
branch 7 taken 57%
-: 239: {
4: 240: uint32 n(this->allocated_size - this->read_pos); // number of bytes to reach the end of buffer
-: 241: return this->read(reinterpret_cast<uint8*>(data), n)
4: 242: + this->read(reinterpret_cast<uint8*>(data)+n, size-n);
call 0 never executed
call 1 never executed
call 2 never executed
call 3 never executed
call 4 returned 100%
call 5 returned 100%
call 6 returned 100%
call 7 returned 100%
-: 243: }
15: 244: memcpy(reinterpret_cast<void*>(data), reinterpret_cast<void*>(this->buf+this->read_pos), size);
15: 245: incrementReadPos(size);
call 0 returned 100%
call 1 returned 100%
call 2 returned 100%
call 3 returned 100%
15: 246: return size;
-: 247: }