Intel Extensible Firmware Interface - Manual (Page 785)

EFI Byte Code Virtual Machine
Version 1.10 12/01/02 19-11
19.7.3 Index/Immediate Data Encoding
Following the operand bytes for most instructions is the instruction’s immediate data. The
immediate data is, depending on the instruction and instruction encoding, either an unsigned or
signed literal value, or an index encoded using natural encoding. In either case, the size of the
immediate data is specified in the instruction encoding.
For most instructions, the index/immediate value in the instruction stream is interpreted as a signed
immediate value if the register operand is direct. This immediate value is then added to the
contents of the register to compute the instruction operand. If the register is indirect, then the data
is usually interpreted as a natural index (see Section 19.4) and the computed index value is added to
the contents of the register to get the address of the operand.
19.8 EBC Instruction Set
The following sections describe each of the EBC instructions in detail. Information includes an
assembly-language syntax, a description of the instruction functionality, binary encoding, and any
limitations or unique behaviors of the instruction.