Numbers

Type records and symbol records may contain instances of the Number type. In the PDB documentation, these are called "numeric leaves".

Example: The S_CONSTANT record contains a Number field which is the value of the constant.

Number contains a numeric value of a given value and type. The type of the number is represented in its encoding, so there is no need for an external specification of the type of the number.

Number is a variable-length data type. Its size can be determined from its encoded form.

The representation of Number always requires at least two bytes. These first two bytes either specify the literal value of the number (with an implied type), or they specify the type and size of the Number. The first two bytes are encoded as a little-endian uint16_t value, and we refer to this uint16_t value as the leaf.

If leaf is less than 0x8000, then the type is implicitly LF_USHORT (an unsigned 16-bit value), the value is simply the leaf value itself, and there are no additional bytes after the first two bytes. This is the simplest case and is very common.

If leaf is greater or equal to 0x8000, then the leaf specifies the type and size of the Number:

Leaf	Leaf Type	Size (bytes)	Description
0x8000	LF_CHAR	1	signed 8-bit integer
0x8001	LF_SHORT	2	signed 16-bit integer
0x8002	LF_USHORT	2	unsigned 16-bit integer
0x8003	LF_LONG	4	signed 32-bit integer
0x8004	LF_ULONG	4	unsigned 32-bit integer
0x8005	LF_REAL32	4	32-bit floating-point
0x8006	LF_REAL64	8	64-bit floating-point
0x8007	LF_REAL80	10	80-bit floating-point
0x8008	LF_REAL128	16	128-bit floating-point
0x8009	LF_QUADWORD	8	signed 64-bit integer
0x800a	LF_UQUADWORD	8	unsigned 64-bit integer
0x800b	LF_REAL48	6	48-bit floating-point
0x800c	LF_COMPLEX32	8	32-bit floating-point complex (real, imaginary)
0x800d	LF_COMPLEX64	16	64-bit floating-point complex (real, imaginary)
0x800e	LF_COMPLEX80	20	80-bit floating-point complex (real, imaginary)
0x800f	LF_COMPLEX128	32	128-bit floating-point complex (real, imaginary)
0x8010	LF_VARSTRING	*	Variable-length string; see below
0x8017	LF_OCTWORD	16	signed 128-bit integer
0x8018	LF_UOCTWORD	16	unsigned 128-bit integer
0x8019	LF_DECIMAL	16	OLE variant decimal value
0x801a	LF_DATE	8	OLE variant date value
0x801b	LF_UTF8STRING	*	UTF-8 NUL-terminated string

In this table, the "Size (Bytes)" column specifies the number of bytes that follow the leaf value; the size does not count the number of bytes in the leaf value itself. For example, the total size of an LF_ULONG number is 6 bytes, not 4 bytes.

There is no leaf value for an unsigned 8-bit value because all unsigned 8-bit values can be stored directly in leaf.

LF_VARSTRING (0x8010)

For LF_VARSTRING, the leaf value is followed by a uint16_t value that specifies the length in bytes of the string data, followed by the length data. There is no alignment padding after the string data.

Examples

Encoded bytes	Leaf Type	Value
00 00	LF_USHORT	0
0a 01	LF_USHORT	266 (0x010a)
00 80 41	LF_CHAR	'A'
01 80 fe ff	LF_SHORT	-2
02 80 fe ff	LF_USHORT	0xfffe
03 80 11 22 00 00	LF_LONG	0x2211
04 80 fe ff ff ff	LF_LONG	-2
04 80 fe ff ff ff	LF_ULONG	0xfffffffe
1b 80 41 42 43 00	LF_UTF8STRING	"ABC"
10 80 04 00 44 45 46	LF_VARSTRING	"DEF"