GE 90-30/20/Micro manual Shfr BIT, Word

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SHFR (BIT, WORD)

Use the Shift Register (SHFR) function to shift one or more data words or data bits from a reference location into a specified area of memory. For example, one word might be shifted into an area of memory with a specified length of five words. As a result of this shift, another word of data would be shifted out of the end of the memory area.

Note

When assigning reference addresses, overlapping input and output reference address ranges in multi-word functions may produce unexpected results.

The SHFR function has four input parameters and two output parameters. The reset input (R) takes precedence over the function enable input. When the reset is active, all references beginning at the shift register (ST) up to the length specified for LEN, are filled with zeros.

If the function receives power flow and reset is not active, each bit or word of the shift register is moved to the next highest reference. The last element in the shift register is shifted into Q. The highest reference of the shift register element of IN is shifted into the vacated element starting at ST. The contents of the shift register are accessible throughout the program because they are overlaid on absolute locations in logic addressable memory.

The function passes power to the right whenever power is received through the enable logic.

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(enable)	(ok)
WORD
(reset) —R	Q— (output parameter Q)
LEN
00001
(value to be shifted) —IN
(first bit or word) —ST

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GFK-0467K Chapter 4 Series 90-30/20/Micro Instructions Set 4-77