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//! SFNT Table Directory
const sfnt = @import("shared").sfnt;
const constants = sfnt.constants;
const ParseError = sfnt.errors.parse.ParseError;
const Reader = sfnt.types.reader.Reader;
const TableRecord = sfnt.types.record.TableRecord;
const limits = constants.limits;
const tags = constants.tags;
pub const Directory = struct {
Data: []const u8,
Records: [limits.MAX_TABLES]TableRecord,
Count: u16,
pub fn parse(data: []const u8) ParseError!Directory {
var reader = Reader.initialize(data);
const version = try reader.readU32();
if (version == tags.VERSION_COLLECTION) {
return ParseError.UnsupportedCollection;
}
if (version == tags.VERSION_OPENTYPE) {
return ParseError.UnsupportedOutlines;
}
if (version != tags.VERSION_TRUETYPE and version != tags.VERSION_TRUE) {
return ParseError.InvalidSignature;
}
const count = try reader.readU16();
if (count > limits.MAX_TABLES) {
return ParseError.TooManyTables;
}
try reader.skip(6);
var directory = Directory{
.Data = data,
.Records = undefined,
.Count = count,
};
var index: u16 = 0;
while (index < count) : (index += 1) {
const tag = try reader.readU32();
_ = try reader.readU32();
const offset = try reader.readU32();
const length = try reader.readU32();
if (offset > data.len or length > data.len - offset) {
return ParseError.TableOutOfBounds;
}
directory.Records[index] = TableRecord{
.Tag = tag,
.Offset = offset,
.Length = length,
};
}
return directory;
}
pub fn find(self: *const Directory, tag: u32) ?[]const u8 {
var index: u16 = 0;
while (index < self.Count) : (index += 1) {
const entry = self.Records[index];
if (entry.Tag == tag) {
return self.Data[entry.Offset .. entry.Offset + entry.Length];
}
}
return null;
}
pub fn require(self: *const Directory, tag: u32) ParseError![]const u8 {
return self.find(tag) orelse ParseError.TableMissing;
}
};
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