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// slang-offset-container.cpp
#include "slang-offset-container.h"
namespace Slang
{
/* !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! OffsetString !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! */
size_t OffsetString::calcEncodedSize(size_t size, uint8_t encode[kMaxSizeEncodeSize])
{
SLANG_ASSERT(size <= 0xffffffff);
if (size <= kSizeBase)
{
encode[0] = uint8_t(size);
return 1;
}
// Encode
int num = 0;
while (size)
{
encode[num + 1] = uint8_t(size);
size >>= 8;
num++;
}
// It might be one byte past the front, if its < 0x100 but greater than kSizeBase
SLANG_ASSERT(num >= 1);
encode[0] = uint8_t(kSizeBase + num);
return num + 1;
}
/* static */ const char* OffsetString::decodeSize(const char* in, size_t& outSize)
{
const uint8_t* cur = (const uint8_t*)in;
if (*cur <= kSizeBase)
{
outSize = *cur;
return in + 1;
}
int numBytes = *cur - kSizeBase;
switch (numBytes)
{
case 1:
{
outSize = cur[1];
return in + 2;
}
case 2:
{
outSize = cur[1] | (uint32_t(cur[2]) << 8);
return in + 3;
}
case 3:
{
outSize = cur[1] | (uint32_t(cur[2]) << 8) | (uint32_t(cur[3]) << 16);
return in + 4;
}
case 4:
{
outSize = cur[1] | (uint32_t(cur[2]) << 8) | (uint32_t(cur[3]) << 16) |
(uint32_t(cur[4]) << 24);
return in + 5;
}
default:
{
outSize = 0;
return nullptr;
}
}
}
/* static */ size_t OffsetString::calcAllocationSize(size_t stringSize)
{
uint8_t encode[kMaxSizeEncodeSize];
size_t encodeSize = calcEncodedSize(stringSize, encode);
// Add 1 for terminating 0
return encodeSize + stringSize + 1;
}
/* static */ size_t OffsetString::calcAllocationSize(const UnownedStringSlice& slice)
{
return calcAllocationSize(slice.getLength());
}
UnownedStringSlice OffsetString::getSlice() const
{
size_t size;
const char* chars = decodeSize(m_sizeThenContents, size);
return UnownedStringSlice(chars, size);
}
const char* OffsetString::getCstr() const
{
return getSlice().begin();
}
/* !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! OffsetContainer !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
*/
OffsetContainer::OffsetContainer()
{
m_capacity = 0;
m_data = nullptr;
// We need to allocate some of the first bytes 0 can be used for nullptr.
allocateAndZero(kStartOffset, 1);
}
OffsetContainer::~OffsetContainer()
{
if (m_data)
{
::free(m_data);
}
}
void* OffsetContainer::allocate(size_t size)
{
return allocate(size, 1);
}
void OffsetContainer::fixAlignment(size_t alignment)
{
allocate(0, alignment);
}
void* OffsetContainer::allocate(size_t size, size_t alignment)
{
size_t offset = (m_dataSize + alignment - 1) & ~(alignment - 1);
if (offset + size > m_capacity)
{
const size_t minSize = offset + size;
size_t calcSize = m_capacity;
if (calcSize < 2048)
{
calcSize = 2048;
}
else
{
// Expand geometrically, but lets not double in size...
calcSize = calcSize + (calcSize / 2);
}
// We must be at least minSize
size_t newSize = (calcSize < minSize) ? minSize : calcSize;
// Reallocate space
m_data = (uint8_t*)::realloc(m_data, newSize);
m_capacity = newSize;
}
SLANG_ASSERT(offset + size <= m_capacity);
m_dataSize = offset + size;
return m_data + offset;
}
void* OffsetContainer::allocateAndZero(size_t size, size_t alignment)
{
void* data = allocate(size, alignment);
memset(data, 0, size);
return data;
}
Offset32Ptr<OffsetString> OffsetContainer::newString(const UnownedStringSlice& slice)
{
size_t stringSize = slice.getLength();
uint8_t head[OffsetString::kMaxSizeEncodeSize];
size_t headSize = OffsetString::calcEncodedSize(stringSize, head);
size_t allocSize = headSize + stringSize + 1;
uint8_t* bytes = (uint8_t*)allocate(allocSize);
::memcpy(bytes, head, headSize);
::memcpy(bytes + headSize, slice.begin(), stringSize);
// 0 terminate
bytes[headSize + stringSize] = 0;
return Offset32Ptr<OffsetString>(getOffset(bytes));
}
Offset32Ptr<OffsetString> OffsetContainer::newString(const char* contents)
{
Offset32Ptr<OffsetString> relString;
if (contents)
{
relString = newString(UnownedStringSlice(contents));
}
return relString;
}
} // namespace Slang
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