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Change how bitfield masks are calculated #29

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merged 1 commit into from
Apr 16, 2024
+19 −27
Merged

Change how bitfield masks are calculated #29

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46 changes: 19 additions & 27 deletions src/dwarf/typereader.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -451,33 +451,19 @@ impl<'elffile> DebugDataReader<'elffile> {
child_entry.offset().to_debug_info_offset(unit).unwrap().0;
if let Some(bit_offset) = get_bit_offset_attribute(child_entry) {
// Dwarf 2 / 3
if self.endian == Endianness::Big {
membertype = TypeInfo {
name: membertype.name.clone(),
unit_idx: membertype.unit_idx,
dbginfo_offset,
datatype: DwarfDataType::Bitfield {
basetype: Box::new(membertype),
bit_size: bit_size as u16,
bit_offset: bit_offset as u16,
},
};
} else {
// Endianness::Little
let type_size = membertype.get_size();
let type_size_bits = type_size * 8;
let bit_offset_le = type_size_bits - bit_offset - bit_size;
membertype = TypeInfo {
name: membertype.name.clone(),
unit_idx: membertype.unit_idx,
dbginfo_offset,
datatype: DwarfDataType::Bitfield {
basetype: Box::new(membertype),
bit_size: bit_size as u16,
bit_offset: bit_offset_le as u16,
},
};
}
let type_size = membertype.get_size();
let type_size_bits = type_size * 8;
let bit_offset_le = type_size_bits - bit_offset - bit_size;
membertype = TypeInfo {
name: membertype.name.clone(),
unit_idx: membertype.unit_idx,
dbginfo_offset,
datatype: DwarfDataType::Bitfield {
basetype: Box::new(membertype),
bit_size: bit_size as u16,
bit_offset: bit_offset_le as u16,
},
};
} else if let Some(mut data_bit_offset) =
get_data_bit_offset_attribute(child_entry)
{
Expand All @@ -491,6 +477,12 @@ impl<'elffile> DebugDataReader<'elffile> {
offset += (data_bit_offset / type_size_bits) * type_size;
data_bit_offset %= type_size_bits;
}
if self.endian == Endianness::Big {
// reverse the mask for big endian. Example
// In: type_size 32, offset: 5, size 4 -> 0000_0000_0000_0000_0000_0001_1110_0000
// Out: offset = 32 - 5 - 4 = 23 -> 0000_0111_1000_0000_0000_0000_0000_0000
data_bit_offset = type_size_bits - data_bit_offset - bit_size;
}
// these values should be independent of Endianness
membertype = TypeInfo {
name: membertype.name.clone(),
Expand Down