logic instruction in RISC-V

* And Immediate 
    * General Form: ANDI   RegD,Reg1,Immed-12
    * Example: ANDI   x4,x9,123       # x4 = x9 & 0x0000007B
    * Description: The immediate value (a sign-extended 12-bit value, i.e., -2,048 .. +2,047) is logically ANDed with the contents of Reg1 and the result is placed in RegD. 
    * Encoding: This is an I-type instruction. 
* And 
    * General Form: AND    RegD,Reg1,Reg2
    * Example: AND    x4,x9,x13     # x4 = x9 & x13
    * Description: The contents of Reg1 is logically ANDed with the contents of Reg2 and the result is placed in RegD. 
    * Encoding:  This is an R-type instruction. 
* Or Immediate 
    * General Form: ORI   RegD,Reg1,Immed-12
    * Example: ORI   x4,x9,123       # x4 = x9 | 0x0000007B
    * Description: The immediate value (a sign-extended 12-bit value, i.e., -2,048 .. +2,047) is logically ORed with the contents of Reg1 and the result is placed in RegD. 
    * Encoding:  This is an I-type instruction.
* Or 
    * General Form: OR    RegD,Reg1,Reg2
    * Example: OR    x4,x9,x13     # x4 = x9 | x13
    * Description: The contents of Reg1 is logically ORed with the contents of Reg2 and the result is placed in RegD. 
    * Encoding:  This is an R-type instruction. 
* Xor Immediate 
    * General Form: XORI   RegD,Reg1,Immed-12
    * Example: XORI   x4,x9,123       # x4 = x9 ^ 0x0000007B
    * Description: The immediate value (a sign-extended 12-bit value, i.e., -2,048 .. +2,047) is logical XORed with the contents of Reg1 and the result is placed in RegD. 
    * Encoding:  This is an I-type instruction.
* Xor 
    * General Form: XOR    RegD,Reg1,Reg2
    * Example: XOR    x4,x9,x13     # x4 = x9 ^ x13
    * Description: The contents of Reg1 is logically XORed with the contents of Reg2 and the result is placed in RegD. 
    * Encoding:  This is an R-type instruction. 
* Not 
    * General Form: NOT     RegD,Reg1
    * Example: NOT     x4,x9     # x4 = ~x9
    * Description: The contents of Reg1 is fetched and each of the bits is 2lipped. The resulting value is copied into RegD. 
    * Encoding: This is a special case of a more general instruction. This instruction is assembled identically to: XORI   RegD,Reg1,-1    # Note that -1 = 0xFFFFFFFF