Bit aligned data block transfer method and apparatus
AssigneeNetwork Computing Devices, Inc.
InventorsJohn R. Providenza, Lee Boekelheide
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Abstract
The number of required clock periods in a bit aligned block transfer operation may be reduced by analyzing the logical relationship between source, destination and pattern operands prior to fetching these operands from memory. If the result of the raster operation can be determined without actually using the value of any of the operands, the result is provided without reading memory values. When the raster operation will have no effect on the existing destination operand, the write operation is also canceled.
Claims12
A graphics system for associating a plurality of operands including at least first and second image operands, each operand being representative of graphics data, said system comprising:
- image modification means for effecting a given logic operation with respect to said plurality of operands for providing an image output in response to said logic operations,
- image data storage means for coding said operands,
- image control means for normally writing said image output tot he address location in said image data storage means of said second operand,
- means for determining the effect of said given logic operation on said second operand, and
- means for inhibiting said image control means from writing said modified image output when said given logic operation is determined to have no effect on said second operand.
A method for block transfer of data in a memory, said transfer being effected according to a predetermined logic expression representative of the respective relationship between source and destination data, said method comprising:
- receiving an operation code representative of said logic expression,
- determining in a first determination from said operation code whether any data needs to be accessed from said memory,
- accessing said data as said data is needed,
- determining form said operation code and data as accessed from said memory whether any data needs to be written into said memory, and
- writing said data into said memory as needed to complete a memory operation.
Dependencies are inferred from the claim text.