2018-2019-1 20165330 "Information Security system Design Fundamentals" Second week study summary

Presentation and processing of learning content summary information

2. Bytes: The smallest addressable memory unit in the computer
4. Virtual Memory: Machine-level programs treat memory as a very large byte array
6. Binary representation and Conversion
   • Decimal: D=dndn-1...d1d0.d-1...d-m (M,n is a positive integer)
   • Binary: B=bnbn-1...b1b0.b-1...b-m (M,n is a positive integer)
   • Octal: O=onon-1...o1o0.o-1 ... 0-m (M,n is a positive integer)
   • Hexadecimal: H=hnhn-1...h1h0.h-1...h-m (M,n is a positive integer), a numeric constant that starts with 0x or 0X in the C language is a value of 16 binary
   • Binary conversions:
     • Decimal conversion R binary: Integer part divided by R, Quotient is weighted until quotient is 0 and below to top; Fractional part is continuously multiplied by the integer portion of R record result and above to below
     • Binary conversion octal: every three bits is an octal, less than the highest bit 0
     • Binary conversion hex: Every four bits is a hexadecimal, less than the highest bit 0
8. For a machine with a W-bit length, the virtual address range is 0~2^w-1 and the program accesses up to 2^w bytes
10. Program instructions that can be run on a 32-bit or 64-bit machine:gcc -m32 prog.c
12. Big-endian rule: the most significant byte is at the front
14. Small-end rule: least significant byte at the front
16. In a computer system, a program is simply a sequence of bytes
18. Bit-level operations
    • Bit vectors: A fixed length of W, composed of 0 and 1 of the string, the vast majority of which can represent a number
    • Bit-level operations include:
      • | Or operation: two x 0 o'clock to 0
      • "&" and operations: 0 is 0
      • "~" Non-operation: the negation
      • "^" XOR: Two of the same number is 0
20. Logical operations
    • In a logical operation, only 0, 12, non-0 parameters indicate that true,0 represents false
    • The logical operations include:
      • "&&": with 1 with true, with 0 with false
      • "| |" : True if operand is true
      • “!” : Take counter
22. Shift Operations
    • Shift left X<<k: Left K-bit, right-most complement K 0
    • Arithmetic right shift x>>k: Move the K-bit right and the value at the left to complement K's most significant bit
    • Logical right Shift x>>>k: Move K-bit right, left complement K 0

    • Use arithmetic right shift for signed number, logical right shift for unsigned number

      Integer representation
24. Information = bit + context
26. unsigned integer: b2u4[0011]=0 2^3+0 2^2+1 2^1+1 2^0=3
28. Signed integer-complement code: B2t4[1011]=-1 2^3+0 2^2+1 2^1+1 2^0=-5
30. Unsigned number means you need to append the suffix character u
32. Floating point number:

2018-2019-1 20165330 "Information Security system Design Fundamentals" Second week study summary