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2. 发明授权

US5594927A Apparatus and method for aligning data transferred via DMA using a barrel shifter and a buffer comprising of byte-wide, individually addressabe FIFO circuits 失效
标题翻译：用于使用桶形移位器和缓冲器对DMA传送的数据进行对准的装置和方法，所述缓冲器包括字节宽的单独的寻址FIFO电路
公开(公告)号：US5594927A
公开(公告)日：1997-01-14
申请号：US306855
申请日：1994-09-15
申请人： Ching S. Lee , Frank A. Itkowsky, Jr.
发明人： Ching S. Lee , Frank A. Itkowsky, Jr.
IPC分类号： G06F13/40 , G06F13/00 , G06F13/38
CPC分类号： G06F13/4018
摘要： An apparatus and method for transferring data via DMA in data processing system from a host system to a transmission network. The transferred data is in longword format in which each longword consists of four bytes. Within a longword, valid bytes intended for transmission are contiguous. The adapter or I/O device includes a packet memory and a FIFO circuit interposed between the host system and packet memory to allow for differences in access speed of a host memory and the packet memory. The FIFO circuit contains four discrete FIFO circuits that are separately addressable for writing the bytes of each longword received from the host memory for storage in the FIFO circuit. The received longword is applied to a barrel shifter which aligns the first valid byte in the received longword with the one of the four discrete FIFO circuits containing a first available storage location at a current FIFO longword address. A FIFO control circuit receives information describing the number of valid bytes in the received longword and generates a control signal to control the barrel shifter and FIFO address signals to cause the valid bytes of the received longword to be stored in contiguous byte positions in the FIFO circuit commencing with the first available storage location.
摘要翻译：一种用于在数据处理系统中通过DMA将数据从主机系统传送到传输网络的装置和方法。传输的数据是长字格式，其中每个长字由四个字节组成。在长字中，用于传输的有效字节是连续的。适配器或I / O设备包括分组存储器和插入在主机系统和分组存储器之间的FIFO电路，以允许主机存储器和分组存储器的访问速度的差异。 FIFO电路包含四个独立可寻址的离散FIFO电路，用于写入从主机存储器接收的每个长字的字节以存储在FIFO电路中。接收的长字被应用于桶形移位器，其将接收的长字中的第一有效字节与包含当前FIFO长字地址的第一可用存储位置的四个离散FIFO电路中的一个对齐。 FIFO控制电路接收描述接收到的长字中的有效字节数的信息，并产生控制信号以控制桶形移位器和FIFO地址信号，以使接收的长字的有效字节存储在FIFO电路中的连续字节位置从第一个可用的存储位置开始。

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