CHAPTER 3 - ASSEMBLER Programming Interface
This chapter gives the technical details of the GRAFIX package. It will give you the necessary information to write an ASSEMBLY language interface for the programming language you are working with. I'm going to assume that anyone who reads this chapter already knows how to program in 80x86 ASSEMBLY language. If you don't then I suggest that you skip this section. It probably will confuse you more than help.
An ASSEMBLY language interface for GRAFIX is the key to writing an interface in another programming language. The BASIC and PASCAL interfaces provided with the package are written in ASSEMBLER. GRAFIX is a memory resident program, all requests to it are done through the video BIOS interrupt. The AH register contains the hexadecimal value EE which indicates to GRAFIX that a function request is about to be made. The AL register contains the function number. The remaining registers BX, CX, DX, SI, DI, and DS contain the parameters of the requested function. For example, if you wanted to draw a solid green box on screen from 0, 0 - 319, 199 the function call would look like this:
MOV AX,0EE11H ;Draw solid box function
MOV BX,0 ;X1 location in BX
MOV CX,0 ;Y1 location in CX
MOV SI,319 ;X2 location in SI
MOV DI,199 ;Y2 location in DI
MOV DX,2 ;Box color in DX
INT 10H ;Call GRAFIX
The next section of this chapter will list each of the GRAFIX functions in numerical order. The format of each function listing is as follows:
Title
Function number
Description
Register entry values
Register exit values
Example
Comments
The title is the name I use for the function in the ASSEMBLY language source file, it is just listed here for reference purposes. The function number is the the value for the AL register, it is listed in decimal format. The description explains what each function does. The register entry values are the values required to execute the function. The exit values are any register values that the function might return to your program. The example is an ASSEMBLY language code fragment showing a call to GRAFIX for that function. The comments section is optional and is included only where I feel extra clarification is needed. Entry values for the AX register for each function are in hexadecimal.
| ClearScreen | Clears the screen viewport to the current background color. |
| ColorEnable | Turns the color enable signal on or off. |
| SetColor | Sets the current drawing, text, or background color. |
| GetColor | Returns the current drawing, text, or background color. |
| SetAspect | Sets the vertical and horizontal elements of the aspect ratio used to draw circles. |
| GetAspect | Returns the current horizontal and vertical portions of the aspect ratio. |
| Point | Plots individual points onto the screen using the current drawing color. |
| GetPoint | Returns the current color of the point at the specified X, Y position. |
| MoveTo | Updates the current X, Y position by replacing the previous X, Y values. |
| MoveRel | Updates the current X, Y position by adding to the previous X, Y values. |
| GetXY | Returns the current X, Y position. |
| Line | Draws a line starting at the upper left X, Y position to the lower right X, Y position using the current drawing color. |
| LineTo | Draws a line from the current X, Y position to specified X, Y position using the current drawing color. |
| LineRel | Draws a line from the current X, Y position adding the number of points horizontally and vertically to get the ending X, Y position. The line is drawn using the current drawing color. |
| DrawBox | Draws a line box starting at the upper left X, Y position to the lower right X, Y position using the specified color. |
| Circle | Draws a circle centered at the specified X, Y position using the specified radius, and current drawing color. |
| Paint | Paints irregular shapes starting at the specified X, Y position using the specified fill color stopping at the specified boundary color. |
| FillBox | Draws a solid box starting at the upper left X, Y position to the lower right X, Y position using the specified color. |
| SetPalette | Sets the specified palette register to the specified color. |
| PaletteUsing | Sets all 16 palette registers using 16 elements of an integer array. |
| ResetPalette | Resets all 16 palette registers to their default state. |
| Get | Stores a graphics image starting at the upper left X, Y position to the lower right X, Y position into an integer array. |
| Put | Transfers an image that was previously stored using the Get function using 1 of 5 actions. |
| SetCursor | Turns the graphics cursor on/off or sets it to full/half size. |
| GetCursor | Returns the current graphics cursor status and size. |
| SetCursorPos | Sets the current graphics cursor position in text format for use with the 'PrintString' function. |
| GetCursorPos | Returns the current graphics cursor position in text format. |
| PrintString | Prints a text string on the graphics screen starting at the current cursor position using the current text color. |
| Animate | Animates an image doing both the initial transfer and final erase all in one step. The delay is the amount of time to pause between the initial transfer and final erase of the image. Use this to minimize flickering. |
| PointC | Plots individual points onto the screen using the specified color. |
| LineC | Draws a line starting at the upper left X, Y position to the lower right X, Y position using the specified color. |
| LineToC | Draws a line starting at the current X, Y position to specified X, Y position using the specified color. |
| LineRelC | Draws a line from the current X, Y position adding the number of points horizontally and vertically to get the ending X, Y position. The line is drawn using the specified color. |
| CircleC | Draws a circle centered at the specified X, Y position using the specified radius, color. |
| DrawBoxC | Draws a line box starting at the upper left X, Y position to the lower right X, Y position using the current drawing color. |
| FillBoxC | Draws a solid box starting at the upper left X, Y position to the lower right X, Y using the current drawing color. |
| XorPoint | XORs individual points onto the screen using the current drawing color. |
| XorPointC | XORs individual points onto the screen using the specified color. |
| XorLine | XORs a line starting at the upper left X, Y position to the lower right X, Y position using the current drawing color. |
| XorLineC | XORs a line starting at the upper left X, Y position to the lower right X, Y position using the specified color. |
| XorLineTo | XORs a line from the current X, Y position to specified X, Y position using the current drawing color. |
| XorLineToC | XORs a line from the current X, Y position to specified X, Y position using the specified color. |
| XorLineRel | XORs a line from the current X, Y position adding the number of points horizontally and vertically to get the ending X, Y position. The line is drawn using the current drawing color. |
| XorLineRelC | XORs a line from the current X, Y position adding the number of points horizontally and vertically to get the ending X, Y position. The line is drawn using the specified color. |
| XorDrawBox | XORs a line box starting at the upper left X, Y position to the lower right X, Y position using the specified color. |
| XorDrawBoxC | XORs a line box starting at the upper left X, Y position to the lower right X, Y position using the current drawing color. |
| XorFillBox | XORs a solid box starting at the upper left X, Y position to the lower right X, Y position using the specified color. |
| XorFillBoxC | XORs a solid box starting at the upper left X, Y position to the lower right X, Y position using the current drawing color. |
| XorCircle | XORs a circle centered at the specified X, Y position using the specified radius, and current drawing color. |
| XorCircleC | XORs a circle centered at the specified X, Y position using the specified radius, and color. |
| Ellipse | Draws an ellipse centered at the specified X, Y position using the specified major and minor axes and current drawing color. |
| EllipseC | Draws an ellipse centered at the specified X, Y position using the specified major and minor axes and color. |
| XorEllipse | XORs an ellipse centered at the specified X, Y position using the specified major and minor axes and current drawing color. |
| XorEllipseC | XORs an ellipse centered at the specified X, Y position using the specified major and minor axes and color. |
| SetView | Sets the size of the current screen viewport. |
| GetView | Returns the size of the current screen viewport. |
| ResetView | Resets the screen viewport to its default size. |
| GetScreen | Copies the entire screen buffer into an integer array. |
| PutScreen | Copies the entire screen from an integer array into the screen buffer. |
| SetDisplayPage | Sets the current display page which will display on the computer monitor. |
| GetDisplayPage | Returns the current display page. |
| SetActivePage | Sets the current active page which all graphic functions will work with. |
| GetActivePage | Returns the current active page. |
| PageCopy | Copies the source video page to the destination video page. |
| System | This is a blanket routine to incorporate many system level functions of the GRAFIX package. |
| Sound | Generates a sound with the specified frequency, duration, volume, and sound channel. |
| Noise | Generates a periodic or white noise sound using the specified type, volume, and duration. |
| Delay | Delays a program the specified number of clock ticks. |
| FastTimer | Sets the speed of the 8253 timer chip. |
| ResetTimer | Resets the 8253 timer chip to its normal speed which is a setting of 1. |
| GetTimer | Returns the current speed of the 8253 timer chip. |