I wrote a NASM program and created a listing file from it using nasm -f elf -l rs.lst rs.asm.
The program, which works perfectly, takes in a key input value, and outputs whether the value is a control key or printable key, and if it is a number, lowercase, or uppercase letter.
I need help understanding what I am reading in the .lst file.
Are the numbers on the left addresses? Instructions? DO they represent memory?
Here's the .lst.
1 segment .data
//Removed my student ID info
8 ;Program Output Strings
9
10 00000023 5072657373204B6579- askForKey: db 'Press Key and Enter: ', 10 ; ;10 is the newline value
11 0000002C 20616E6420456E7465-
12 00000035 723A200A
13 askLen: equ $-askForKey
14
15 00000039 436F6E74726F6C204B- controlKey: db 'Control Key ', 10
16 00000042 6579200A
17 controlLen: equ $-controlKey
18
19 00000046 5072696E7461626C65- printableKey: db 'Printable Key ', 10
20 0000004F 204B6579200A
21 printableLen: equ $-printableKey
22
23 00000055 446563696D616C204B- decimalKey: db 'Decimal Key ', 10
24 0000005E 6579200A
25 decimalLen: equ $-decimalKey
26
27 00000062 55707065722D636173- upperKey: db 'Upper-case Key ', 10
28 0000006B 65204B6579200A
29 upperLen: equ $-upperKey
30
31 00000072 4C6F7765722D636173- lowerKey: db 'Lower-case Key ', 10
32 0000007B 65204B6579200A
33 lowerLen: equ $-lowerKey
34
35 00000082 0A blankLine: db '', 10
36 blankLen: equ $-blankLine
37
38 segment .bss
39
40 00000000 <res 00000002> key resb 2
41
42 segment .text
43
44 global main
45 main:
46
47
48 00000000 B804000000 mov eax, 4 ; system call 4
49 00000005 BB01000000 mov ebx, 1 ; standard output
50 0000000A B9[00000000] mov ecx, studentInfo ; 'Program by Raphael Stein'
51 0000000F BA23000000 mov edx, infoLen
52 00000014 CD80 int 0x80
53
54 ;Program Begins
55
56 ; Ask for key input
57 00000016 B804000000 mov eax, 4 ; system call 4
58 0000001B BB01000000 mov ebx, 1 ; standard output
59 00000020 B9[23000000] mov ecx, askForKey ; 'Press key and Enter: '
60 00000025 BA16000000 mov edx, askLen
61 0000002A CD80 int 0x80
62 ; Take input
63 0000002C B803000000 mov eax, 3 ; system call 3 to get input
64 00000031 BB00000000 mov ebx, 0 ; standart input device
65 00000036 B9[00000000] mov ecx, key ; pointer to id
66 0000003B BA02000000 mov edx, 2 ; take in this many bytes
67 00000040 CD80 int 0x80
68
69
70
71 control: ; check if it's a control key
72 00000042 B120 mov cl, 32 ; space bar (32) is the first key after control keys
73 00000044 BB[00000000] mov ebx, key ;move the first 8bits of ebx for comparison
74 00000049 380B cmp byte [ebx], cl ; compare 32 and the value of key
75 0000004B 7D1B jge printable ; If the key is >=, it's a printable
76 0000004D B804000000 mov eax, 4
77 00000052 BB01000000 mov ebx, 1
78 00000057 B9[39000000] mov ecx, controlKey
79 0000005C BA0D000000 mov edx, controlLen
80 00000061 CD80 int 0x80
81 00000063 E9A0000000 jmp exit ; It's obviously not any of the other categories
82
83
84 printable: ; Tell that it's a printable symbol
85 00000068 B804000000 mov eax, 4
86 0000006D BB01000000 mov ebx, 1
87 00000072 B9[46000000] mov ecx, printableKey
88 00000077 BA0F000000 mov edx, printableLen
89 0000007C CD80 int 0x80
90
91 decimal:
92 0000007E B130 mov cl, 48 ; 0 (48) is the smallest decimal
93 00000080 BB[00000000] mov ebx, key ;move the first 8bits of ebx for comparison
94 00000085 380B cmp byte [ebx], cl
95 00000087 7C7F jl exit
96 00000089 B139 mov cl, 57 ; 9 (57) is the largest decimal
97 0000008B BB[00000000] mov ebx, key ;move the first 8bits of ebx for comparison
98 00000090 380B cmp byte [ebx], cl
99 00000092 7F18 jg uppercase ; if key is greater, jump to check if it's uppercase.
100 00000094 B804000000 mov eax, 4
101 00000099 BB01000000 mov ebx, 1
102 0000009E B9[55000000] mov ecx, decimalKey
103 000000A3 BA0D000000 mov edx, decimalLen
104 000000A8 CD80 int 0x80
105 000000AA EB5C jmp exit
106
107 uppercase:
108 000000AC B141 mov cl, 65 ; A (65) is the smallest smallest uppercase
109 000000AE BB[00000000] mov ebx, key ;move the first 8bits of ebx for comparison
110 000000B3 380B cmp byte [ebx], cl
111 000000B5 7C51 jl exit
112 000000B7 B15A mov cl, 90 ; Z (90) is the largest upper case
113 000000B9 BB[00000000] mov ebx, key ;move the first 8bits of ebx for comparison
114 000000BE 380B cmp byte [ebx], cl
115 000000C0 7F18 jg lowercase
116 000000C2 B804000000 mov eax, 4 ; If it IS an upper case key, print and then exit
117 000000C7 BB01000000 mov ebx, 1
118 000000CC B9[62000000] mov ecx, upperKey
119 000000D1 BA10000000 mov edx, upperLen
120 000000D6 CD80 int 0x80
121 000000D8 EB2E jmp exit
122
123
124 lowercase:
125 000000DA B161 mov cl, 97 ; a (97) is the smallest smallest uppercase
126 000000DC BB[00000000] mov ebx, key ;move the first 8bits of ebx for comparison
127 000000E1 380B cmp byte [ebx], cl
128 000000E3 7C23 jl exit ; If the key is less than 97 exit.
129 000000E5 B17A mov cl, 122 ; Z (90) is the largest upper case
130 000000E7 BB[00000000] mov ebx, key ;move the first 8bits of ebx for comparison
131 000000EC 380B cmp byte [ebx], cl
132 000000EE 7FEA jg lowercase
133 000000F0 B804000000 mov eax, 4 ; If it IS an upper case key, print and then exit
134 000000F5 BB01000000 mov ebx, 1
135 000000FA B9[72000000] mov ecx, lowerKey
136 000000FF BA10000000 mov edx, lowerLen
137 00000104 CD80 int 0x80
138 00000106 EB00 jmp exit
139
140 exit:
141 00000108 B804000000 mov eax, 4 ; system call 4
142 0000010D BB01000000 mov ebx, 1 ; standard output
143 00000112 B9[82000000] mov ecx, blankLine ; Print blank line before exiting
144 00000117 BA01000000 mov edx, blankLen
145 0000011C CD80 int 0x80
146
147 0000011E B801000000 mov eax, 1
148 00000123 31DB xor ebx, ebx
149 00000125 CD80 int 0x80
150
https://stackoverflow.com/questions/16154870
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