public OperationStatus ReadFrom(
ReadOnlySpan <byte> span,
out CopyCommand copy)
{
if (span.Length < _minSize)
{
copy = default;
return(OperationStatus.NeedMoreData);
}
byte command = span[0];
const byte minCommand = _baseCommand +
4 * (byte)CommandModifier.OneByte +
(byte)CommandModifier.OneByte;
const byte maxCommand = _baseCommand +
4 * (byte)CommandModifier.EightBytes +
(byte)CommandModifier.EightBytes;
if (command < minCommand || command > maxCommand)
{
copy = default;
return(OperationStatus.InvalidData);
}
command -= _baseCommand;
var startModifier = (CommandModifier)(command >> 2);
var opStatus = CommandArg.ReadFrom(
span.Slice(1),
startModifier,
out var startArg);
if (opStatus != OperationStatus.Done)
{
copy = default;
return(opStatus);
}
var lengthModifier = (CommandModifier)(command & 0x03);
opStatus = CommandArg.ReadFrom(
span.Slice(1 + startArg.Size),
lengthModifier,
out var lengthArg);
if (opStatus != OperationStatus.Done)
{
copy = default;
return(opStatus);
}
copy = new CopyCommand(startArg, lengthArg);
return(OperationStatus.Done);
}
public OperationStatus ReadFrom(
ReadOnlySpan <byte> span,
out LiteralCommand literal)
{
if (span.Length < _minSize)
{
literal = default;
return(OperationStatus.NeedMoreData);
}
byte command = span[0];
const byte maxCommand = _baseCommand + (byte)CommandModifier.EightBytes;
if (command == 0 || command > maxCommand)
{
literal = default;
return(OperationStatus.InvalidData);
}
else if (command < _baseCommand)
{
literal = new LiteralCommand(length: command);
return(OperationStatus.Done);
}
var argModifier = (CommandModifier)(command - _baseCommand);
var opStatus = CommandArg.ReadFrom(
span.Slice(1),
argModifier,
out var arg);
if (opStatus != OperationStatus.Done)
{
literal = default;
return(opStatus);
}
literal = new LiteralCommand(arg);
return(OperationStatus.Done);
}
