Claims
- 1. A video graphics system, comprising:
- a display medium having pixel locations arranged in rows with the address location between adjacent rows defined in terms of pitch used for converting X-Y memory addresses consisting of separate X coordinates and Y coordinates into linear physical locations on said display;
- a video presentation memory having established locations therein corresponding to each said pixel location;
- a register for controlling said conversion, said register including a first section storing a first value and a second section storing a second value; and
- circuitry connected to said register for converting pixel display medium address locations from said memory from said X-Y address format used within said memory to said linear addresses based upon said digits in said register, said circuitry
- if said first value of said first section of said register has a predetermined value, performing a full multiplication of said Y coordinate and said pitch,
- if said first value of said first section of said register does not have said predetermined value and said second value is zero, shifting said Y coordinate by said first value number of places forming a first resultant, and
- if said first value of said first section of said register does not have said predetermined value and said second value is not zero, shifting said Y coordinate by said first value number of places forming a first resultant, shifting said Y coordinate by said second value number of places forming a second resultant, and adding said first resultant and said second resultant forming a third resultant.
- 2. The video graphics system of claim 1, wherein:
- said predetermined value is zero.
- 3. A method of calculating the linear address of a graphical display from presented X-Y binary value coordinates, said display having a number of bits within each pixel in the X direction and a pitch dimension, expressed in binary format, between rows in the Y direction, said method comprising the steps of:
- accessing a first register to determine a first value contained therein;
- based upon a determined first value different from a designated value, indicating that the pitch is an exact power of two or that the pitch is calculated to be the sum of two powers of two, shifting a presented Y coordinate binary value a number of places dependent upon said first value to obtain a first resultant value;
- based upon said shifting of said Y coordinate, accessing a second register to determine a second value contained therein;
- based upon a determined positive second value, shifting said presented Y coordinate binary value a number of places dependent upon said second value to obtain a second resultant value;
- adding together said first and second resultant values; and
- based upon a determined first value equal to said designated value, indicating that the pitch is neither an exact power of two nor the sum of two powers of two, enabling a full multiplication of said presented Y coordinate binary number by said binary pitch dimension to obtain a third resultant value.
- 4. The method as set forth in claim 3 further including the steps of:
- shifting a presented X coordinate binary value a number of places dependent upon the size of each pixel to obtain a fourth resultant value; and
- adding together selected combinations of said first, second, third and fourth resultant values to obtain said linear address corresponding to said presented X and Y coordinates.
- 5. The method of claim 4 wherein one of said selected combinations comprises said first and fourth resultant values.
- 6. The method of claim 4 wherein one of said selected combinations comprises said third and fourth resultant values.
- 7. The method of claim 4 wherein one of said selected combinations comprises said second and fourth resultant values.
- 8. The method of claim 3, wherein:
- said designated value is zero.
Parent Case Info
This application is a continuation of U.S. patent application Ser. No. 07/735,203 filed Jul. 24, 1991 and now abandoned, which is a continuation of U.S. patent application Ser. No. 07/386,057 filed Jul. 23, 1989 and now abandoned.
US Referenced Citations (11)
Continuations (2)
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Number |
Date |
Country |
Parent |
735203 |
Jul 1991 |
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Parent |
386057 |
Jul 1989 |
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