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EP4SE530F35I4 数据表(PDF) 49 Page - Altera Corporation |
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EP4SE530F35I4 数据表(HTML) 49 Page - Altera Corporation |
49 / 432 page Chapter 2: Logic Array Blocks and Adaptive Logic Modules in Stratix IV Devices 2–13 Adaptive Logic Modules February 2011 Altera Corporation Stratix IV Device Handbook Volume 1 Carry Chain The carry chain provides a fast carry function between the dedicated adders in arithmetic or shared-arithmetic mode. The two-bit carry select feature in Stratix IV devices halves the propagation delay of carry chains within the ALM. Carry chains can begin in either the first ALM or the fifth ALM in the LAB. The final carry-out signal is routed to the ALM, where it is fed to local, row, or column interconnects. The Quartus II Compiler automatically creates carry-chain logic during design processing, or you can create it manually during design entry. Parameterized functions such as LPM functions automatically take advantage of carry chains for the appropriate functions. The Quartus II Compiler creates carry chains longer than 20 (10 ALMs in arithmetic or shared arithmetic mode) by linking LABs together automatically. For enhanced fitting, a long carry chain runs vertically, allowing fast horizontal connections to TriMatrix memory and DSP blocks. A carry chain can continue as far as a full column. To avoid routing congestion in one small area of the device when a high fan-in arithmetic function is implemented, the LAB can support carry chains that only use either the top half or bottom half of the LAB before connecting to the next LAB. This leaves the other half of the ALMs in the LAB available for implementing narrower fan-in functions in normal mode. Carry chains that use the top five ALMs in the first LAB carry into the top half of the ALMs in the next LAB within the column. Carry chains that use the bottom five ALMs in the first LAB carry into the bottom half of the ALMs in the next LAB within the column. In every alternate LAB column, the top half can be bypassed; in the other MLAB columns, the bottom half can be bypassed. For more information about carry-chain interconnects, refer to “ALM Interconnects” on page 2–18. |
类似零件编号 - EP4SE530F35I4 |
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类似说明 - EP4SE530F35I4 |
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