1                                  
     2                                  
     3                                  section	.data
     4                                  
     5                                  
     6                                  
     7                                  image_info_address EQU 8  ; First argument passed to our function starts from 8
     8                                  first_piece_address EQU 12 ; From that point we just add 4 to address of next
     9                                  ; arguments
    10                                  piece_to_swap_with_address EQU 16
    11                                  horizontal_divisons_address EQU 20
    12                                  piece_width_address EQU 24
    13                                  piece_height_address EQU 28
    14                                  piece_width_bytes_address EQU 32
    15                                  piece_height_bytes_address EQU 36
    16                                  bytes_per_row_address EQU 40
    17                                  firstPieceStartingByte EQU 44
    18                                  secondPieceStartingByte EQU 48
    19                                  
    20                                  
    21                                  pImg_inside_image_info_address EQU 12
    22                                  
    23                                  
    24                                  image_width		EQU 0
    25                                  image_height		EQU 4
    26                                  bytes_per_row_inside_image_info_address	EQU 8
    27                                  image_pImg		EQU	12
    28                                  image_pHeaderInfo	EQU 16 ; not really used
    29                                  
    30                                  ; first.X, first.Y, second.X, second.Y
    31                                  
    32                                  
    33                                  
    34                                  %macro print 2      ;number of arguments this macro takes
    35                                    mov	edx, %1       ;message length
    36                                    mov	ecx, %2       ;message to write
    37                                    mov	ebx,1         ;file descriptor (stdout)
    38                                    mov	eax,4         ;system call number (sys_write)
    39                                    int	0x80          ;call kernel
    40                                  %endmacro
    41                                  
    42                                  
    43                                  
    44                                  section	.text
    45                                  global inner_loops     ;must be declared for linker (ld)
    46                                  ; extern void hello_world(imageInfo* pInfo, int firstPiece, int pieceToSwapWith,
    47                                  ;												int horizontalDivisions, int pieceWidth,
    48                                  ;												int pieceHeight);
    49                                  
    50                                  ; mov	ecx, [ebp + 8]	; ecx <- address of imgInfo struct, not saved
    51                                  ; mov eax, [ebp + 12]	; eax <- firstPiece, not saved
    52                                  ; mov edx, [ebp + 16] ; edx <- pieceToSwapWith, not saved
    53                                  ; mov esi, [ecx + image_pImg] ; esi <- start of pixels in picture, saved
    54                                  ; mov ebx, [ebp + 20] ; ebx <- horizontalDivisions
    55                                  ; mov edi, [ebp + 24] ; edi <- pieceWidth
    56                                  
    57                                  inner_loops:	          ;tells linker entry point
    58                                  
    59 00000000 55                        push ebp  ; as per calling convention we need to keep the values of
    60                                    ; certain registers
    61 00000001 89E5                      mov ebp,esp
    62 00000003 53                        push ebx
    63 00000004 56                        push esi
    64 00000005 57                        push edi
    65                                  
    66                                    ; what we use:
    67                                    ; ecx - firstPieceFirstByteAddress
    68                                    ; edx - secondPieceFirstByteAddress
    69                                    ; esi
    70                                    ; edi
    71                                  
    72                                    ; what we have:
    73                                    ; eax
    74                                    ; ebx
    75                                  
    76 00000006 53                        push ebx
    77 00000007 50                        push eax
    78                                    ;mov eax, [ebp + firstPieceStartingByte]
    79                                    ;mov eax, [eax + image_pImg]
    80 00000008 BF00000000                mov edi, 0
    81                                  
    82                                  x_pixels_loop:
    83 0000000D 3B7D20                      cmp edi, [ebp + piece_width_bytes_address]
    84                                      ;cmp edi, 300
    85 00000010 7D42                        jge x_pixels_loop_end
    86 00000012 BE00000000                  mov esi, 0
    87                                  
    88                                    ; ecx = secondPieceStartingByte
    89                                    ; edx = firstPieceStartingByte
    90                                    ; we still have eax and ebx
    91                                    ;
    92                                    y_pixels_loop:
    93 00000017 3B7524                      cmp esi, [ebp + piece_height_bytes_address]
    94                                      ;cmp esi, 96000
    95 0000001A 7D33                        jge y_pixels_loop_end
    96 0000001C 8B4D30                      mov ecx, [ebp + secondPieceStartingByte]
    97 0000001F 8B452C                      mov eax, [ebp + firstPieceStartingByte]
    98 00000022 01F9                        add ecx, edi
    99 00000024 01F1                        add ecx, esi
   100 00000026 01F8                        add eax, edi
   101 00000028 01F0                        add eax, esi
   102                                  
   103 0000002A 8A18                        mov BYTE bl, [eax]
   104 0000002C 8A11                        mov BYTE dl, [ecx]
   105 0000002E 8819                        mov BYTE[ecx], bl
   106 00000030 8810                        mov BYTE[eax], dl
   107                                  
   108 00000032 8A5801                      mov BYTE bl, [eax + 1]
   109 00000035 8A5101                      mov BYTE dl, [ecx + 1]
   110 00000038 885901                      mov BYTE[ecx + 1], bl
   111 0000003B 885001                      mov BYTE[eax + 1], dl
   112                                  
   113 0000003E 8A5802                      mov BYTE bl, [eax + 2]
   114 00000041 8A5102                      mov BYTE dl, [ecx + 2]
   115 00000044 885902                      mov BYTE[ecx + 2], bl
   116 00000047 885002                      mov BYTE[eax + 2], dl
   117                                  
   118                                  
   119                                  
   120 0000004A 037528                      add esi, [ebp + bytes_per_row_address]
   121 0000004D EBC8                        jmp y_pixels_loop
   122                                  
   123                                  
   124                                    ; 		for(x = 0; x < pieceWidth * 3; x += 3)
   125                                    y_pixels_loop_end:
   126 0000004F 83C703                      add edi, 3
   127 00000052 EBB9                        jmp x_pixels_loop
   128                                  
   129                                    x_pixels_loop_end:
   130                                  
   131 00000054 5E                        pop esi
   132 00000055 5F                        pop edi
   133 00000056 5B                        pop ebx
   134 00000057 89EC                      mov esp, ebp
   135 00000059 5D                        pop ebp
   136 0000005A C3                        ret