mirror of
https://github.com/vxunderground/MalwareSourceCode.git
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183 lines
3.0 KiB
NASM
183 lines
3.0 KiB
NASM
;
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; grafix --- cgagrafa.asm
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;
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; stuff to plot points fast in 8086 assembler (BLEECH!!!)
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;
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; Written 4/87 by Scott Snyder (ssnyder@romeo.caltech.edu or @citromeo.bitnet)
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;
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; Modified 5/29/87 by sss to allow for different memory models
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;
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title cgagrafa
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include macros.ah
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sseg
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endss
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g_oddoff equ 02000h
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g_linsiz equ 80
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dseg
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ex g_drawbuf, dword
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ex g_pixbyte, word
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ex g_bitpix, word
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ex g_colormask, byte
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ex g_cmask_tbl, byte
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ex g_hicolormask, byte
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ex g_xor, word
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ex g_xcliplo, word
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ex g_xcliphi, word
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ex g_ycliplo, word
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ex g_ycliphi, word
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endds
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cseg _cgagrafa
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; plot a point. ax = y; bl = c; cx = x;
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pBegin plot
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les si, g_drawbuf ; get address of buffer
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sar ax, 1 ; y /= 2
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jnc p1 ; add in offset if it was odd
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add si, g_oddoff
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p1: mov dx, g_linsiz ; y * g_linsiz
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mul dx
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add si, ax ; add to offset
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mov ax, cx ; x to AC (ohhh... what symmetry!)
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mov dx, 0
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div g_pixbyte
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add si, ax ; add quotient to offset (now complete)
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and bl, g_colormask ; get cmask
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mov bl, g_cmask_tbl[bx]
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mov cx, g_bitpix ; only works for bitpix = 0 or 1!
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dec cx
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shl dx, cl ; dx = mask shift count
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mov cx, dx
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mov dl, g_hicolormask ; get mask
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shr dl, cl ; shift it
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and bx, dx ; bx = cmask & mask
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mov al, es:[si] ; get image byte
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cmp g_xor, 0 ; xor mode?
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jne p2
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not dl ; no - (*ptr & ~mask) | (cmask & mask)
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and al, dl
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or al, bl
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jmp p3
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p2: xor al, bl ; yes - *ptr ^ (cmask & mask)
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p3: mov es:[si], al ; done!
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ret
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pEnd plot
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;
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; C interface for point plotter
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;
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; CGA_point(x, y, c)
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;
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pBegin CGA_point
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push bp
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mov bp, sp
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push si
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push di
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mov ax, [bp+argbase+2]
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mov bx, [bp+argbase+4]
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mov cx, [bp+argbase]
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call plot
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pop di
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pop si
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mov sp, bp
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pop bp
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ret
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pEnd CGA_point
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;
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; write for pixels for circle drawing
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;
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; void CGA_write_pix(x1, y1, x2, y2, c)
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;
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pBegin CGA_write_pix
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push bp
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mov bp, sp
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push si
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push di
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mov bx, [bp+argbase+8] ; bx = c (for plot)
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mov cx, [bp+argbase] ; cx = x1
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cmp cx, g_xcliplo ; check for clipping
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jb w2
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cmp cx, g_xcliphi
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ja w2
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mov ax, [bp+argbase+2] ; ax = y1
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cmp ax, g_ycliplo ; do clipping
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jb w1
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cmp ax, g_ycliphi
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ja w1
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push bx ; plot (x1, y1)
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push cx
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call plot
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pop cx
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pop bx
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w1: mov ax, [bp+argbase+6] ; ax = y2
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cmp ax, g_ycliplo
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jb w2
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cmp ax, g_ycliphi
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ja w2
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push bx ; plot (x1, y2)
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call plot
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pop bx
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w2: mov cx, [bp+argbase+4] ; cx = x2
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cmp cx, g_xcliplo
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jb w4
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cmp cx, g_xcliphi
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ja w4
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mov ax, [bp+argbase+2] ; ax = y1
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cmp ax, g_ycliplo ; do clipping
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jb w3
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cmp ax, g_ycliphi
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ja w3
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push bx ; plot (x2, y1)
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push cx
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call plot
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pop cx
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pop bx
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w3: mov ax, [bp+argbase+6] ; ax = y2
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cmp ax, g_ycliplo
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jb w4
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cmp ax, g_ycliphi
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ja w4
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call plot ; plot (x2, y2)
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w4: pop di
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pop si
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mov sp, bp
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pop bp
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ret
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pEnd CGA_write_pix
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df_ CGA_point
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df_ CGA_write_pix
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endcs _cgagrafa
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end
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