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DATE: April 5, 2016, 4:55 p.m.

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  1. ;*********** WINDLX Ex.1: Read a positive integer number *************
  2. ;*********** (c) 1991 Günther Raidl *************
  3. ;*********** Modified 1992 Maziar Khosravipour *************
  5. ;-----------------------------------------------------------------------------
  6. ;Subprogram call by symbol "InputUnsigned"
  7. ;expect the address of a zero-terminated prompt string in R1
  8. ;returns the read value in R1
  9. ;changes the contents of registers R1,R13,R14
  10. ;-----------------------------------------------------------------------------
  12. .data
  14. ;*** Data for Read-Trap
  15. ReadBuffer: .space 80
  16. ReadPar: .word 0,ReadBuffer,80
  18. ;*** Data for Printf-Trap
  19. PrintfPar: .space 4
  21. SaveR2: .space 4
  22. SaveR3: .space 4
  23. SaveR4: .space 4
  24. SaveR5: .space 4
  27. .text
  29. .global InputSigned
  30. InputSigned:
  31. ;*** save register contents
  32. sw SaveR2,r2
  33. sw SaveR3,r3
  34. sw SaveR4,r4
  35. sw SaveR5,r5
  37. ;*** Prompt
  38. sw PrintfPar,r1
  39. addi r14,r0,PrintfPar
  40. trap 5
  42. ;*** call Trap-3 to read line
  43. addi r14,r0,ReadPar
  44. trap 3
  46. ;*** determine value
  47. addi r2,r0,ReadBuffer
  48. addi r1,r0,0
  49. addi r4,r0,10 ;Decimal system
  51. petla: ;*** reads digits to end of line
  52. lbu r3,0(r2)
  54. ;odczytujemy jaki znak stoi na 1 miejscu +,-,czy moze liczba bez znaku
  57. snei r5, r3, #45 ;jezeli - to do znakminus
  58. beqz r5, minus
  59. snei r5, r3, #43 ;i jesli sa rowne to ustawi sie na 0
  60. beqz r5, plus
  61. snei r5,r3,#10 ;LF -> Exit jak wczyta entera to zkaonczy wczytywanie tego ciagu
  62. beqz r5,Finish
  63. subi r3,r3,#48 ;´0´
  64. multu r1,r1,r4 ;Shift decimal
  65. add r1,r1,r3
  66. addi r2,r2,#1 ;increment pointer
  67. snei r5,r3,#10 ;LF -> Exit
  68. beqz r5,Finish
  69. j petla
  72. minus:
  73. addi r6,r0,#-1 ;zaznaczamy że liczba ujemna
  75. addi r2,r2,#1 ;zwiekszamy increment pointer
  76. j petla
  77. plus:
  79. addi r2,r2,1 ;zwiekszamy increment pointer
  80. j petla
  81. ujemna:
  82. addi r7,r7,#-1 ;ladujemy do r7 -1
  83. mult r1,r1,r7 ;mnożymy r1 razy -1 zeby otrzymac liczbe ujemna
  84. addi r6,r0,#0 ;zeruje r6
  85. addi r7,r0,#0 ;zeruje r7
  86. Finish: ;*** restore old register contents
  87. bnez r6,ujemna
  88. lw r2,SaveR2
  89. lw r3,SaveR3
  90. lw r4,SaveR4
  91. lw r5,SaveR5
  92. jr r31
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