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;**************************************************************************

;**********************DECODING BMP FILE(1,4,8,24 bits)*********************

;***************************************************************************

; BMPTOIMG -Convert BMP format TO IMG format

;***************************************************************************

bmptoimg:

    mov [bmp_load_area],esi

    mov [img_dest_area],edi

    xor eax,eax

    mov ax,word[esi+28]

    mov ebx,[esi+14]

    mov ecx,[esi+18]

    mov edx,[esi+22]

    mov [bmp_bits_per_pixel],ax

    mov [bmp_first_structure_size],ebx

    mov [Bmp_SizeY],edx

    mov [Bmp_SizeX],ecx

    xor eax,eax

    mov ax,[esi+28]

    mul  dword [esi+18]

    add  eax,31

    shr  eax,5

    mov  dword [bmptoimg_data_area_dwps],eax  ;dwps-doublewords per string

    shl  eax,2

    mov  dword [bmptoimg_data_area_bps],eax   ;bps-bytes per string

    cmp dword [esi+34],0

    jne  yespicsize  ;if picture size is defined

    mul dword [esi+22]

    mov dword [esi+34],eax

  yespicsize:

    mov  eax,[bmp_load_area]

    add  eax, [esi+10]	 ;how mach bytes to begin bitmap

    add  eax, [esi+34]	 ;size of bitmap in BMP file

    mov  dword [bmptoimg_data_area_eop],eax   ;eop-end of picture in file

    ;calculate bytes per string

    mov  eax, [esi+18]

    lea  eax,[eax+2*eax]   ;3x pixels in eax

    mov [bmp_bytes_per_string],eax

    mov esi,dword [bmptoimg_data_area_eop]

    sub esi,dword [bmptoimg_data_area_bps]

    mov ebp,[img_dest_area]

    mov edi,[img_dest_area]

    mov ebx,[bmp_load_area]

    add ebx, [bmp_first_structure_size]

    add ebx,14		;in ebx start of color table

    cmp [bmp_bits_per_pixel],24

    je	convert_to_24bpp

    cmp [bmp_bits_per_pixel],8

    je convert_to_8bpp

    cmp [bmp_bits_per_pixel],4

    je convert_to_4bpp

    cmp [bmp_bits_per_pixel],1

    je convert_to_1bpp

    jmp end_bmp

;--------------------------------------------------

;-----------Decoding 24 bit BMP file---------------

;--------------------------------------------------

convert_to_24bpp:

  mov ebx,[Bmp_SizeY]

  loop_convert_to_24bpp_y:

    mov edi,ebp

    mov  ecx,[bmptoimg_data_area_dwps]

     cld

     rep movsd

    sub  esi,[bmptoimg_data_area_bps]

    sub  esi,[bmptoimg_data_area_bps]

    add  ebp,eax

    dec ebx

    jnz loop_convert_to_24bpp_y

    jmp  end_bmp

;-----------------------------------------------------

;--------------Decoding 8 bits BMP file---------------

;-----------------------------------------------------

 convert_to_8bpp:

    mov ebp,[Bmp_SizeY]

    loop_convert_8bpp_y:

      mov ecx,[bmptoimg_data_area_bps]

      push edi

      loop_convert_8bpp_x:

	 xor eax,eax

	 mov al,byte [esi]

	 call converttable

	 inc esi

	 add edi,3

      dec ecx

      jnz loop_convert_8bpp_x

      pop edi

    add edi,[bmp_bytes_per_string]

    sub esi,[bmptoimg_data_area_bps]

    sub esi,[bmptoimg_data_area_bps]

    dec ebp

    jnz loop_convert_8bpp_y

    jmp end_bmp

;-----------------------------------------------------

;--------------Decoding 4 bits BMP file---------------

;-----------------------------------------------------

 convert_to_4bpp:

    mov ebp,[Bmp_SizeY]

    loop_convert_4bpp_y:

      mov ecx,[bmptoimg_data_area_bps]

      push edi

      loop_convert_4bpp_x:

	 mov [Bmp_save1],ecx

	 xor eax,eax

	 mov al,byte [esi]

	 xor ecx,ecx

	 mov cl,al

	 shr al,4   ;first pixel in byte

	 and cl,0xf ;second pixel in byte

	 call converttable   ;draw first pixel of byte

	 mov eax,ecx	       ;move second pixel to register al and draw

	 add edi,3

	 call converttable   ;draw second pixel of byte

	 add edi,3

	 mov ecx,[Bmp_save1]

	 inc esi

      dec ecx

      jnz loop_convert_4bpp_x

      pop edi

    add edi,[bmp_bytes_per_string]

    sub esi,[bmptoimg_data_area_bps]

    sub esi,[bmptoimg_data_area_bps]

    dec ebp

    jnz loop_convert_4bpp_y

    jmp end_bmp

;-----------------------------------------------------

;---------------Decoding 1 bit BMP file---------------

;-----------------------------------------------------

 convert_to_1bpp:

    mov ebp,[Bmp_SizeY]

    loop_convert_1bpp_y:

      mov ecx,[bmptoimg_data_area_bps]

      push edi

      loop_convert_1bpp_x:

	 xor eax,eax

	 mov al,byte [esi]

	 mov [Bmp_save1],ecx

	 mov  ecx,eax

	 mov  edx,7

	 nextbit:

	    xor  eax,eax

	    bt	 ecx,edx

	    jnc  noaddelem

	    inc  eax

	    noaddelem:

	    push edx

	    call converttable

	    pop  edx

	    add  edi,3

	    dec  edx

	 jns nextbit

	 mov ecx,[Bmp_save1]

	 inc esi

      dec ecx

      jnz loop_convert_1bpp_x

      pop edi

    add edi,[bmp_bytes_per_string]

    sub esi,[bmptoimg_data_area_bps]

    sub esi,[bmptoimg_data_area_bps]

    dec ebp

    jnz loop_convert_1bpp_y

    jmp end_bmp

;-----------------------------------------------------

  converttable:

    shl  eax,2

    add  eax,ebx

    mov  edx, dword [eax]

    mov [edi],edx

    ret

;-----------------------------------------------------

; DATA AREA

bmptoimg_data_area_bps	    dd 0

bmptoimg_data_area_dwps     dd 0

bmptoimg_data_area_eop	    dd 0

bmp_load_area		    dd 0

img_dest_area		    dd 0

bmp_bits_per_pixel	    dw 0

bmp_first_structure_size    dd 0

bmp_bytes_per_string	    dd 0

end_bmp:

ret