30 lines
715 B
Go
30 lines
715 B
Go
package x64
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// regReg encodes an operation using 2 registers.
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func regReg(code []byte, reg byte, rm byte, opCodes ...byte) []byte {
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w := byte(1) // Indicates a 64-bit register.
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r := byte(0) // Extension to the "reg" field in ModRM.
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x := byte(0) // Extension to the SIB index field.
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b := byte(0) // Extension to the "rm" field in ModRM or the SIB base (r8 up to r15 use this).
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mod := byte(0b11) // Direct addressing mode, no register offsets.
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if reg > 0b111 {
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r = 1
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reg &= 0b111
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}
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if rm > 0b111 {
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b = 1
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rm &= 0b111
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}
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rex := REX(w, r, x, b)
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modRM := ModRM(mod, reg, rm)
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code = append(code, rex)
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code = append(code, opCodes...)
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code = append(code, modRM)
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return code
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}
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