Intel 64 and IA-32 Developer’s Manual instruction set glossary

rel8

A relative address in the range from 128 bytes before the end of the instruction to 127 bytes after the end of the instruction

rel16, rel32

A relative address within the same code segment as the instruction assembled. The rel16 symbol applies to instructions with an operand‐size attribute of 16 bits; the rel32 symbol applies to instructions with an operand‐size attribute of 32 bits

ptr16:16, ptr16:32

A far pointer, typically to a code segment different from that of the instruction. The notation 16:16 indicates that the value of the pointer has two parts. The value to the left of the colon is a 16‐bit selector or value destined for the code segment register. The value to the right corresponds to the offset within the destination segment. The ptr 16:16 symbol is used when the instruction’s operand‐size attribute is 16 bits; the ptr16:32 symbol is used when the operand‐size attribute is 32 bits

r8

One of the byte general‐purpose registers: AL, CL, DL, BL, AH, CH, DH, BH, BPL, SPL, DIL, and SIL; or one of the byte registers (R8B–R15B) available when using REX.R and 64‐bit mode

r16

One of the word general‐purpose registers: AX, CX, DX, BX, SP, BP, SI, DI; or one of the word registers (R8–R15) available when using REX.R and 64‐bit mode

r32

One of the doubleword general‐purpose registers: EAX, ECX, EDX, EBX, ESP, EBP, ESI, EDI; or one of the doubleword registers (R8D–R15D) available when using REX.R in 64‐bit mode

r64

One of the quadword general‐purpose registers: RAX, RBX, RCX, RDX, RDI, RSI, RBP, RSP, R8–R15. These are available when using REX.R and 64‐bit mode

imm8

An immediate byte value. The imm8 symbol can be a signed number between −128 and +127 inclusive; an unsigned number between 0 and 255 inclusive; or a bitmap when an instruction uses its individual bits. For instructions in which imm8 is combined with a word or doubleword operand, the immediate value is sign‐extended to form a word or doubleword. The upper byte of the word is filled with the topmost bit of the immediate value

imm16

An immediate word value used for instructions whose operand‐size attribute is 16 bits. This is number between −32,768 and +32,767 inclusive

imm32

An immediate doubleword value used for instructions whose operand‐size attribute is 32 bits. It allows the use of a number between +2,147,483,647 and −2,147,483,648 inclusive

imm64

An immediate quadword value used for instructions whose operand‐size attribute is 64 bits. The value allows the use of a number between +9,223,372,036,854,775,807 and −9,223,372,036,854,775,808 inclusive

/ib

A single‐byte value

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