| 摘要 |
The present invention includes a system, method, and article of manufacture for decompressing a bit stream of compressed data representing a plurality of image blocks. This includes a two-step method of processing both a DC code and a plurality of AC codes. With respect to the processing of the AC codes, a plurality of bits of compressed input data relating to the AC codes are first retrieved from the bit stream. A first decoding operation is then executed based on the obtained compressed input data in order to generate first output data. It is then determined whether sufficient space is available for the first output data. If it is determined that there is sufficient space for the first output data, the first output data is outputted. On the other hand, if it is determined that there is insufficient space for the first output data, an alternate second decoding operation is executed in order to generate second output data. In order to carry out the foregoing decoding operations, a data structure is provided in a look-up table for being employed by the AC decoder during use. Such data structure includes a plurality of data segments each having a payload and a pointer. The payload includes a plurality of bits in one of a plurality of coding schemes. Further, the pointer corresponds to a routine which is capable of processing the coding scheme of the payload associated with the pointer. The first decoding operation first includes the step of performing a look-up in the look-up table based on the obtained compressed input data. The pointer is then retrieved from one of the data segments that corresponds to the obtained compressed input data. Next, the routine corresponding to the retrieved pointer is executed. The payload is then processed in the executed routine in order to generate the first output data. The foregoing routine that processes the payload of the data segment in order to generate the first output data may take many forms.
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