Intel® Extended Memory 64 Technology Software Developer's Guide

• ib, iw, id, io — A 1-byte (ib), 2-byte (iw), 4-byte (id) or 8-byte (io) immediate operand to the instruction thatfollows the opcode, ModR/M bytes or scale-indexing bytes. The opcode determines if the operand is a signedvalue. All words and doublewords are given with the low-order byte first.• +rb, +rw, +rd, +ro — A register code, from 0 through 7, added to the hexadecimal byte given at the left of theplus sign to form a single opcode byte. The register codes are given in Table 2-1.• +i — A number used in floating-point instructions when one of the operands is ST(i) from the FPU register stack.The number i (which can range from 0 to 7) is added to the hexadecimal byte given at the left of the plus sign toform a single opcode byte.Register REX.R RegFieldRegister REX.R RegFieldTable 2-1 Register CodesRegister REX.R RegField2.1.1.2. Instruction Column in the Instruction Summary TableRegister REX.R RegFieldAL 0 0 AX 0 0 EAX 0 0 RAX 0 0CL 0 1 CX 0 1 ECX 0 1 RCX 0 1DL 0 2 DX 0 2 EDX 0 2 RDX 0 2BL 0 3 BX 0 3 EBX 0 3 RBX 0 3AH No REXprefix4 SP No REXprefix4 ESP No REXprefix4 N/A N/A N/ACHDHBHSPLBPLSILDILNo REXprefixNo REXprefixNo REXprefixAny REXPrefixAny REXPrefixAny REXPrefixAny REXPrefix5 BP No REXprefix6 SI No REXprefix7 DI No REXprefix5 EBP No REXprefix6 ESI No REXprefix7 EDI No REXprefix5 N/A N/A N/A6 N/A N/A N/A7 N/A N/A N/A4 SP 0 4 ESP 0 4 RSP 0 45 BP 0 5 EBP 0 5 RBP 0 56 SI 0 6 ESI 0 6 RSI 0 67 DI 0 7 EDI 0 7 RDI 0 7R8L 1 0 R8W 1 0 R8D 1 0 R8 1 0R9L 1 1 R9W 1 1 R9D 1 1 R9 1 1R10L 1 2 R10W 1 2 R10D 1 2 R10 1 2R11L 1 3 R11W 1 3 R11D 1 3 R11 1 3R12L 1 4 R12W 1 4 R12D 1 4 R12 1 4R13L 1 5 R13W 1 5 R13D 1 5 R13 1 5R14L 1 6 R14W 1 6 R14D 1 6 R14 1 6R15L 1 7 R15W 1 7 R15D 1 7 R15 1 7The “Instruction” column gives the syntax of the instruction statement as it would appear in an ASM386 program. Thefollowing is a list of the symbols used to represent operands in the instruction statements:• rel8 — A relative address in the range from 128 bytes before the end of the instruction to 127 bytes after the endof the instruction.• rel16 and rel32 — A relative address within the same code segment as the instruction assembled. The rel16symbol applies to instructions with an operand-size attribute of 16 bits; the rel32 symbol applies to instructionswith an operand-size attribute of 32 bits.2-2 Vol. 1