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//! Optimized for performance in debug builds.
const std = @import("../std.zig");
const MemoryAccessor = std.debug.MemoryAccessor;
const FixedBufferReader = @This();
buf: []const u8,
pos: usize = 0,
endian: std.builtin.Endian,
pub const Error = error{ EndOfBuffer, Overflow, InvalidBuffer };
pub fn seekTo(fbr: *FixedBufferReader, pos: u64) Error!void {
if (pos > fbr.buf.len) return error.EndOfBuffer;
fbr.pos = @intCast(pos);
}
pub fn seekForward(fbr: *FixedBufferReader, amount: u64) Error!void {
if (fbr.buf.len - fbr.pos < amount) return error.EndOfBuffer;
fbr.pos += @intCast(amount);
}
pub inline fn readByte(fbr: *FixedBufferReader) Error!u8 {
if (fbr.pos >= fbr.buf.len) return error.EndOfBuffer;
defer fbr.pos += 1;
return fbr.buf[fbr.pos];
}
pub fn readByteSigned(fbr: *FixedBufferReader) Error!i8 {
return @bitCast(try fbr.readByte());
}
pub fn readInt(fbr: *FixedBufferReader, comptime T: type) Error!T {
const size = @divExact(@typeInfo(T).int.bits, 8);
if (fbr.buf.len - fbr.pos < size) return error.EndOfBuffer;
defer fbr.pos += size;
return std.mem.readInt(T, fbr.buf[fbr.pos..][0..size], fbr.endian);
}
pub fn readIntChecked(
fbr: *FixedBufferReader,
comptime T: type,
ma: *MemoryAccessor,
) Error!T {
if (ma.load(T, @intFromPtr(fbr.buf[fbr.pos..].ptr)) == null)
return error.InvalidBuffer;
return fbr.readInt(T);
}
pub fn readUleb128(fbr: *FixedBufferReader, comptime T: type) Error!T {
return std.leb.readUleb128(T, fbr);
}
pub fn readIleb128(fbr: *FixedBufferReader, comptime T: type) Error!T {
return std.leb.readIleb128(T, fbr);
}
pub fn readAddress(fbr: *FixedBufferReader, format: std.dwarf.Format) Error!u64 {
return switch (format) {
.@"32" => try fbr.readInt(u32),
.@"64" => try fbr.readInt(u64),
};
}
pub fn readAddressChecked(
fbr: *FixedBufferReader,
format: std.dwarf.Format,
ma: *MemoryAccessor,
) Error!u64 {
return switch (format) {
.@"32" => try fbr.readIntChecked(u32, ma),
.@"64" => try fbr.readIntChecked(u64, ma),
};
}
pub fn readBytes(fbr: *FixedBufferReader, len: usize) Error![]const u8 {
if (fbr.buf.len - fbr.pos < len) return error.EndOfBuffer;
defer fbr.pos += len;
return fbr.buf[fbr.pos..][0..len];
}
pub fn readBytesTo(fbr: *FixedBufferReader, comptime sentinel: u8) Error![:sentinel]const u8 {
const end = @call(.always_inline, std.mem.indexOfScalarPos, .{
u8,
fbr.buf,
fbr.pos,
sentinel,
}) orelse return error.EndOfBuffer;
defer fbr.pos = end + 1;
return fbr.buf[fbr.pos..end :sentinel];
}
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