feat: decode int64 prop

Author: akiver

internal/bitread/bitread.go

@@ -16,6 +16,7 @@ const (
 	smallBuffer      = 512
 	largeBuffer      = 1024 * 128
 	maxVarInt32Bytes = 5
+	maxVarintBytes   = 10
 )
 
 // BitReader wraps github.com/markus-wa/gobitread.BitReader and provides additional functionality specific to CS:GO demos.
@@ -67,12 +68,33 @@ func (r *BitReader) ReadVarInt32() uint32 {
 	return res
 }
 
+// ReadVarInt64 reads a variable size unsigned int (max 64-bit).
+func (r *BitReader) ReadVarInt64() uint64 {
+	var (
+		res uint64
+		b   uint64 = 0x80
+	)
+
+	for count := uint(0); b&0x80 != 0 && count != maxVarintBytes; count++ {
+		b = uint64(r.ReadSingleByte())
+		res |= (b & 0x7f) << (7 * count)
+	}
+
+	return res
+}
+
 // ReadSignedVarInt32 reads a variable size signed int (max 32-bit).
 func (r *BitReader) ReadSignedVarInt32() int32 {
 	res := r.ReadVarInt32()
 	return int32((res >> 1) ^ -(res & 1))
 }
 
+// ReadSignedVarInt64 reads a variable size signed int (max 64-bit).
+func (r *BitReader) ReadSignedVarInt64() int64 {
+	res := r.ReadVarInt64()
+	return int64((res >> 1) ^ -(res & 1))
+}
+
 // ReadUBitInt reads some kind of variable size uint.
 // Honestly, not quite sure how it works.
 func (r *BitReader) ReadUBitInt() uint {

pkg/demoinfocs/sendtables/propdecoder.go

@@ -91,6 +91,7 @@ var propDecoder propertyDecoder
 type PropertyValue struct {
 	VectorVal r3.Vector
 	IntVal    int
+	Int64Val  int64
 	ArrayVal  []PropertyValue
 	StringVal string
 	FloatVal  float32
@@ -123,6 +124,9 @@ func (propertyDecoder) decodeProp(prop *property, reader *bit.BitReader) {
 	case propTypeString:
 		prop.value.StringVal = propDecoder.decodeString(reader)
 
+	case propTypeInt64:
+		prop.value.Int64Val = propDecoder.decodeInt64(prop.entry.prop, reader)
+
 	default:
 		panic(fmt.Sprintf("Unknown prop type %d", prop.entry.prop.rawType))
 	}
@@ -144,6 +148,36 @@ func (propertyDecoder) decodeInt(prop *sendTableProperty, reader *bit.BitReader)
 	return reader.ReadSignedInt(prop.numberOfBits)
 }
 
+func (propertyDecoder) decodeInt64(prop *sendTableProperty, reader *bit.BitReader) int64 {
+	if prop.flags.hasFlagSet(propFlagVarInt) {
+		if prop.flags.hasFlagSet(propFlagUnsigned) {
+			return int64(reader.ReadVarInt64())
+		}
+
+		return reader.ReadSignedVarInt64()
+	} else {
+		var high uint = 0
+		var low uint = 0
+		var isNegative bool = false
+		if prop.flags.hasFlagSet(propFlagUnsigned) {
+			low = reader.ReadInt(32)
+			high = reader.ReadInt(prop.numberOfBits - 32)
+		} else {
+			isNegative = reader.ReadBit()
+			low = reader.ReadInt(32)
+			high = reader.ReadInt(prop.numberOfBits - 32 - 1)
+		}
+
+		var result int64 = (int64(high) << 32) | int64(low)
+
+		if isNegative {
+			result = -result
+		}
+
+		return result
+	}
+}
+
 func (propertyDecoder) decodeFloat(prop *sendTableProperty, reader *bit.BitReader) float32 {
 	if prop.flags&specialFloatFlags != 0 {
 		return propDecoder.decodeSpecialFloat(prop, reader)