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refactor: optimize attribute loading with improved byte swap handling #29

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Merged
Beforerr merged 1 commit into from
Nov 3, 2025
Merged

refactor: optimize attribute loading with improved byte swap handling #29

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19 changes: 11 additions & 8 deletions src/loading/attribute.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -9,8 +9,9 @@ Load all attribute entries for a given attribute from its AEDRs.
@inline function load_attribute_entries(buffer::Vector{UInt8}, adr, RecordSizeType, cdf_encoding)
head = max(adr.AgrEDRhead, adr.AzEDRhead)
offsets = get_offsets(buffer, head, RecordSizeType)
needs_byte_swap = is_big_endian_encoding(cdf_encoding)
return map(offsets) do offset
load_aedr_data(buffer, offset, RecordSizeType, cdf_encoding)
load_aedr_data(buffer, offset, RecordSizeType, needs_byte_swap)
end
end

Expand All @@ -19,7 +20,7 @@ end

Load all attributes from the CDF file.
"""
function attrib(cdf::CDFDataset; predicate=is_global)
function attrib(cdf::CDFDataset; predicate = is_global)
RecordSizeType = recordsize_type(cdf)
buffer = cdf.buffer
cdf_encoding = cdf.cdr.encoding
Expand Down Expand Up @@ -59,14 +60,15 @@ function vattrib(cdf::CDFDataset, varnum::Integer)
RecordSizeType = recordsize_type(cdf)
buffer = cdf.buffer
cdf_encoding = cdf.cdr.encoding
attributes = Dict{String,Union{String,Vector}}()
attributes = Dict{String, Union{String, Vector}}()
offsets = get_offsets_lazy(buffer, cdf.gdr.ADRhead, RecordSizeType)
needs_byte_swap = is_big_endian_encoding(cdf_encoding)
for offset in offsets
is_global(buffer, offset, RecordSizeType) && continue
adr = ADR(buffer, offset, RecordSizeType)
for head in (adr.AgrEDRhead, adr.AzEDRhead)
head == 0 && continue
found = _search_aedr_entries(buffer, head, RecordSizeType, cdf_encoding, varnum)
found = _search_aedr_entries(buffer, head, RecordSizeType, needs_byte_swap, varnum)
isnothing(found) && continue
name = String(adr.Name)
attributes[name] = _get_attributes(name, found, cdf)
Expand Down Expand Up @@ -99,13 +101,14 @@ function vattrib(cdf, varnum, name)
# Search for the specific attribute by name first
offsets = get_offsets_lazy(buffer, cdf.gdr.ADRhead, RecordSizeType)
name_bytes = codeunits(name)
needs_byte_swap = is_big_endian_encoding(cdf_encoding)
for offset in offsets
is_global(buffer, offset, RecordSizeType) && continue
adr = ADR(buffer, offset, RecordSizeType)
adr.Name != name_bytes && continue
for head in (adr.AgrEDRhead, adr.AzEDRhead)
head == 0 && continue
found = _search_aedr_entries(buffer, head, RecordSizeType, cdf_encoding, varnum)
found = _search_aedr_entries(buffer, head, RecordSizeType, needs_byte_swap, varnum)
isnothing(found) && continue
return _get_attributes(name, found, cdf)
end
Expand All @@ -114,15 +117,15 @@ function vattrib(cdf, varnum, name)
return nothing
end

@inline function _search_aedr_entries(source, aedr_head, RecordSizeType, cdf_encoding::Int32, target_varnum)
@inline function _search_aedr_entries(source, aedr_head, RecordSizeType, needs_byte_swap, target_varnum)
aedr_head == 0 && return nothing
offset = Int(aedr_head)
_num_offset = 13 + 2 * sizeof(RecordSizeType)
_next_offset = 5 + sizeof(RecordSizeType)
while offset != 0
num = read_be(source, offset + _num_offset, Int32)
if num == target_varnum
return load_aedr_data(source, offset, RecordSizeType, cdf_encoding)
return load_aedr_data(source, offset, RecordSizeType, needs_byte_swap)
end
offset = Int(read_be(source, offset + _next_offset, RecordSizeType))
end
Expand All @@ -134,7 +137,7 @@ end

Return a list of attribute names in the CDF file.
"""
function attribnames(cdf::CDFDataset; predicate=is_global)
function attribnames(cdf::CDFDataset; predicate = is_global)
names = String[]
buffer = cdf.buffer
RecordSizeType = recordsize_type(cdf)
Expand Down
3 changes: 1 addition & 2 deletions src/records/aedr.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,7 @@ struct AEDR{FST, A}
Value::A # This consists of the number of elements (specified by the NumElems field) of the data type (specified by the DataType field). This can be thought of as a 1-dimensional array of values (stored contiguously). The size of this field is the product of the number of elements and the size in bytes of each element.
end

function load_aedr_data(buffer::Vector{UInt8}, offset, RecordSizeType, cdf_encoding)
function load_aedr_data(buffer::Vector{UInt8}, offset, RecordSizeType, needs_byte_swap)
_datatype_offset = 9 + 2 * sizeof(RecordSizeType)
_numelems_offset = 17 + 2 * sizeof(RecordSizeType)
_data_offset = 41 + 2 * sizeof(RecordSizeType)
Expand All @@ -31,7 +31,6 @@ function load_aedr_data(buffer::Vector{UInt8}, offset, RecordSizeType, cdf_encod
return if datatype in (CDF_CHAR, CDF_UCHAR)
load_char_data(buffer, offset + _data_offset, NumElems)
else
needs_byte_swap = is_big_endian_encoding(cdf_encoding)
load_attribute_data(T, buffer, offset + _data_offset, NumElems, needs_byte_swap)
end
end
Expand Down