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AK: Make LEB128 capable of reading into any type

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And not just ssize_t/size_t.
This is useful in cases where the output size is supposed to be larger
than size_t.
This commit is contained in:
Ali Mohammad Pur 2021-04-27 17:58:02 +04:30 • committed by Andreas Kling
parent 48260b5054
commit d288f6654e
1 changed files with 9 additions and 8 deletions
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17
AK/LEB128.h
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@ -12,8 +12,8 @@
namespace AK { namespace AK {
struct LEB128 { struct LEB128 {
template<typename StreamT> template<typename StreamT, typename ValueType = size_t>
static bool read_unsigned(StreamT& stream, size_t& result) static bool read_unsigned(StreamT& stream, ValueType& result)
{ {
[[maybe_unused]] size_t backup_offset = 0; [[maybe_unused]] size_t backup_offset = 0;
if constexpr (requires { stream.offset(); }) if constexpr (requires { stream.offset(); })
@ -35,7 +35,7 @@ struct LEB128 {
if (input_stream.has_any_error()) if (input_stream.has_any_error())
return false; return false;
result = (result) | (static_cast<size_t>(byte & ~(1 << 7)) << (num_bytes * 7)); result = (result) | (static_cast<ValueType>(byte & ~(1 << 7)) << (num_bytes * 7));
if (!(byte & (1 << 7))) if (!(byte & (1 << 7)))
break; break;
++num_bytes; ++num_bytes;
@ -44,9 +44,10 @@ struct LEB128 {
return true; return true;
} }
template<typename StreamT> template<typename StreamT, typename ValueType = ssize_t>
static bool read_signed(StreamT& stream, ssize_t& result) static bool read_signed(StreamT& stream, ValueType& result)
{ {
using UValueType = MakeUnsigned<ValueType>;
[[maybe_unused]] size_t backup_offset = 0; [[maybe_unused]] size_t backup_offset = 0;
if constexpr (requires { stream.offset(); }) if constexpr (requires { stream.offset(); })
backup_offset = stream.offset(); backup_offset = stream.offset();
@ -67,13 +68,13 @@ struct LEB128 {
input_stream >> byte; input_stream >> byte;
if (input_stream.has_any_error()) if (input_stream.has_any_error())
return false; return false;
result = (result) | (static_cast<size_t>(byte & ~(1 << 7)) << (num_bytes * 7)); result = (result) | (static_cast<UValueType>(byte & ~(1 << 7)) << (num_bytes * 7));
++num_bytes; ++num_bytes;
} while (byte & (1 << 7)); } while (byte & (1 << 7));
if (num_bytes * 7 < sizeof(size_t) * 4 && (byte & 0x40)) { if (num_bytes * 7 < sizeof(UValueType) * 4 && (byte & 0x40)) {
// sign extend // sign extend
result |= ((size_t)(-1) << (num_bytes * 7)); result |= ((UValueType)(-1) << (num_bytes * 7));
} }
return true; return true;