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Under MIB addressing, the base and displacement are used to compute an effective address as base + displacement. [ 1 ] : §3.1.1.3 The register specified by the SIB byte's INDEX field does not participate in this effective-address calculation, but is instead treated as a separate input argument to the instructions using this addressing mode.
The PC-relative addressing mode can be used to load a register with a value stored in program memory a short distance away from the current instruction. It can be seen as a special case of the "base plus offset" addressing mode, one that selects the program counter (PC) as the "base register".
Base-plus-index and scale-plus-index addressing require the SIB byte, which encodes 2-bit scale factor as well as 3-bit index and 3-bit base registers. Depending on the addressing mode, Disp8/Disp16/Disp32 field may follow with displacement that needs to be added to the address. The EVEX prefix retains fields introduced in the VEX prefix:
MIPS I has instructions that load and store 8-bit bytes, 16-bit halfwords, and 32-bit words. Only one addressing mode is supported: base + displacement. Since MIPS I is a 32-bit architecture, loading quantities fewer than 32 bits requires the datum to be either sign-extended or zero-extended to 32 bits.
A computer program can access an address given explicitly – in low-level programming this is usually called an absolute address, or sometimes a specific address, and is known as pointer data type in higher-level languages. But a program can also use relative address which specifies a location in relation to somewhere else (the base address).
In computing, a base address is an address serving as a reference point ("base") for other addresses. Related addresses can be accessed using an addressing scheme.. Under the relative addressing scheme, to obtain an absolute address, the relevant base address is taken and an offset (aka displacement) is added to it.
Format 4: Only valid on SIC/XE machines, consists of the same elements as format 3, but instead of a 12-bit displacement, stores a 20-bit address. Both format 3 and format 4 have six-bit flag values in them, consisting of the following flag bits: n: Indirect addressing flag; i: Immediate addressing flag; x: Indexed addressing flag
Bits 0-3 of byte 1 specify either a register number or a modifier; bits 4-7 of byte 1 specify the number of the general register to be used as an index; bytes 2-3 specify a base and displacement. SI (four bytes). Byte 1 specifies an immediate field; bytes 2-3 specify a base and displacement. SS (six bytes). Byte 1 specifies two 4-bit length ...