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Extensible Firmware Interface Specification
19-48 12/01/02 Version 1.10
NEG
SYNTAX:
NEG[32|64] {@}R
1
, {@}R
2
{Index16|Immed16}
DESCRIPTION:
Multiply Operand 2 by negative 1, and store the result back to Operand 1. Operand 2 is a signed
value and fetched as either a 32-bit (NEG32) or 64-bit (NEG64) value.
OPERATION
Operand 1 <= -1 * Operand 2
Table 19-34. NEG Instruction Encoding
BYTE DESCRIPTION
Bit Description
7 0 = Operand 2 immediate/index absent
1 = Operand 2 immediate/index present
6 0 = 32-bit operation
1 = 64-bit operation
0
0..5 Opcode = 0x0B
Bit Description
7 0 = Operand 2 direct
1 = Operand 2 indirect
4..6 Operand 2
3 0 = Operand 1 direct
1 = Operand 1 indirect
1
0..2 Operand 1
2..3 Optional 16-bit immediate data/index
BEHAVIORS AND RESTRICTIONS:
• If Operand 2 is indirect, then the immediate data is interpreted as an index, and the Operand 2
value is fetched from memory as a signed value at address [R
2
+ Index16].
• If Operand 2 is direct, then the immediate data is considered a signed immediate value and is
added to the Operand 2 register contents such that Operand 2 = R
2
+ Immed16.
• If the instruction is NEG32 and Operand 1 is direct, then the result is stored in Operand 1
register with the upper 32-bits cleared.