6 RiscV

base integer instructions

• Base 47 instructions

• there are 32 registers

  • $x0\to x32$

Main memory

• memory is a large 1-D array

  • each address is a 8 bit (byte)

• Little endian

  • where th e LSB

• Memory operand example

  • A[12]=h+A[8]
    • h in x21, bas adress of A in x22
      • so we would be taking to

Operands

• immediate operands

  • immediate operands skip load instruction

    • only small constants allowed
    • end with an “i”

  • addi

    • constant specific addition
    • addi x22, x22, 4

• register operands

  • basic type
  • limmited by the # of registers

• memory operands

  • load and store

Integer numbers

• human number (base 10)

  • machine like binar number (base 2)

  • in any number base the value off the i-th digit is

    • $d\ast bas{e}^i$

• types of integer numbers

  • unsigned and signed

• instructions → number

  • ie stored program concept (slide 5)

Assembly to binary

• C program

  • A[30] ok but we want assembly we need to store it 120(x10) x10 is the instruction and 120 is the bit repsentation of the array in binary so it adds the offset
• if you want to put an array into another array but he complement of it you can just xor with -i then wow