Statement List (STL) - DCE FEL ČVUT v Praze

Floating-Point Math Instructions
8.4.2 SQRT Generate the Square Root of a Floating-Point Number
(32-Bit)
Format
SQRT
Description of instruction
Result
Example
SQRT (generate the square root of a 32-bit, IEEE-FP floating-point number)
calculates the square root of a floating-point number (32-bit, IEEE-FP) in ACCU 1.
The result is stored in accumulator 1. The input value must be greater than or equal
to zero. The result is then positive. Only exception the square root of -0 is -0. The
instruction influences the CC 1, CC 0, OV, and OS status word bits.
The contents of accumulator 2 (and also the contents of accumulator 3 and
accumulator 4 for CPUs with four ACCUs) remain unchanged.
The result in ACCU 1 is CC 1 CC 0 OV OS Note
+qNaN 1 1 1 1
+infinite 1 0 1 1 Overflow
+normalized 1 0 0 -
+denormalized 0 0 1 1 Underflow
+zero 0 0 0 -
-zero 0 0 0 -
-qNaN 1 1 1 1
STL Explanation
L MD10 //The value from memory double word MD10 is loaded into ACCU 1. (This
value must be in the floating-point format.)
SQRT //Calculate the square root of the floating-point number (32-bit,
IEEE-FP) in ACCU 1. Store the result in ACCU 1.
AN OV //Scan the OV bit in the status word for "0."
JC OK //If no error occurred during the SQRT instruction, jump to the OK jump
label.
BEU //Block end unconditional, if an error occurred during the SQRT
instruction.
OK: T MD20 //Transfer the result from ACCU 1 to memory double word MD20.
Statement List (STL) for S7-300 and S7-400 Programming
A5E00706960-01 8-11