| 摘要 |
PURPOSE:To perform the pipeline processing in the generation of a constant and to calculate a constant for back projection processing at a high speed by providing adders, subtractors and multipliers in the same number as the number of times of addition, subtraction and multiplication in constant generating operation using the outputs of table memories and connecting the table memories, the adders, the subtractors and the multipliers through shift registers capable of holding the midway result of the constant generating operation. CONSTITUTION:A principal operation result in the generation of a constant for back projection processing is obtained by accessing table memories 57, 61, 69, 87, 92 and the operation using said result is performed by adders ADD, subtractors SUB and multipliers MPY. Herein, the adders ADD, the subtractors SUB and the multipliers MPY are provided in the same number as the number of times of addition, subtraction and multiplication in constant generating operation and coupled with each other by registers SCK and, therefore, the pipeline processing in the generation of a constant becomes possible. As a result, the constant for back projection processing can be equivalently generated in one cycle and the generation speed of the constant can be increased as compared with a conventional case generating the constant by requiring several ten cycles. |
