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Il_Voza

4.2 Conversion bin to dec + logic operations bit-to-bit

May 12th, 2013
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  1. ;Write a program that acquires two variables of type byte opA and opB in binary format by keyboard ('0' and '1' sequence) and writes the result of logic operation bitwise into a variable of type byte ris.
  2. ;Logic expression bit-to-bit is:
  3. ;C = NOT(A AND (NOT(B))) OR (A XOR B).
  4.  
  5. ;IMPLEMENTATION
  6. ;Acquisition binary values:
  7. ;-It's need conversion of ASCII character read by keyboard
  8. ;-User types binary values (ex.:“00011100”) separated by ENTER
  9. ;Logic operations on byte carried out with specific instructions
  10.  
  11. DIM EQU 8     ;Dimension of every binary number... 8bit
  12. .MODEL small
  13. .STACK
  14. .DATA
  15. opa DB ?
  16. opb DB ?
  17. ris DB ?
  18. .CODE
  19. .STARTUP
  20. MOV ah,1
  21. XOR bx,bx
  22. MOV CX,DIM
  23. ;The first cycle concerns first variable opa
  24. ciclo1: int 21h    ;In input I can insert only 0 or 1
  25.         SUB AL,'0'
  26.         DEC CX
  27.         SHL AL,CL  ;SHL and OR instructions convert my binary number to decimal number. SHL does: AL*2^CL. In a cycle is, for example: 1*2^7+0*2^6+1*2^5+etc... that is the conversion from binary to decimal
  28.         OR BL,AL   ;L'OR sums in BL the values in decimal that corresponds at the bit at 1
  29.         CMP CX,0
  30.         JNZ ciclo1
  31. INT 21h        
  32. MOV opa,BL  ;puts the converted number (to decimal) in opa
  33. xor BX,BX
  34. MOV CX,DIM
  35. ciclo2: int 21h       ;This 2° cycle concerns opb
  36.         SUB AL,'0'
  37.         DEC CX
  38.         SHL AL,CL
  39.         OR BL,AL
  40.         CMP CX,0
  41.         JNZ ciclo2
  42.        
  43. MOV opb,BL   ;put the decimal result in opb
  44. ;Below there are the required logic operations by the text
  45. MOV al,opb
  46. not al
  47. and al,opa
  48. not al
  49. mov ah,opa
  50. xor ah,opb
  51. or al,ah
  52. mov ris,al
  53.  
  54. .exit
  55. END  
  56.  
  57. ;Then, since the text is unclear,
  58. ;the text asks to write in input into two
  59. ;variables 2 binary numbers, and convert them to decimal
  60. ;and then to apply that logic operations that asks
  61. ;at the end; so that logic operations are done
  62. ;on operands with decimal value, because then the assembler
  63. ;considers however the binary numbers since the logic operations
  64. ;work bit-to-bit
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