ISUB – Integer subtraction

Block SymbolLicensing group: STANDARD

Function Description
The ISUB block subtracts two integer input signals $n = i1 - i2$ . The range of integer numbers in a computer is always restricted by the variable type. This block uses the vtype parameter to specify the type. If the difference fits in the range of the given type, the result is the ordinary sum. In the other cases the result depends on the SAT parameter.

The overflow is not checked for $SAT = off$ , i.e. the output $E = off$ and the output value n corresponds with the arithmetics of the processor. E.g. for the Short type, which has the range of -32768..+32767, we obtain 30000 - -2770 = -32766

For $SAT = on$ the overflow results in setting the error output to $E = on$ and the n output to the nearest displayable value. For the above mentioned example we get 30000 - -2770 = 32767.

This block propagates the signal quality. More information can be found in the 1.4 section.

Input

i1	First integer input of the block $↓$ -9.22E+18 $↑$ 9.22E+18	Long (I32)
i2	Second integer input of the block $↓$ -9.22E+18 $↑$ 9.22E+18	Long (I32)

Parameter

vtype	Numeric type $⊙$ 4	Long (I32)
	2 .... Byte (U8) 3 .... Short (I16) 4 .... Long (I32) 5 .... Word (U16) 6 .... DWord (U32) 10 ... Large (I64)
SAT	Saturation (overflow) checking	Bool
	off .. Overflow is not checked on ... Overflow is checked

Output

n	Integer difference between the input signals	Long (I32)
E	Error indicator	Bool
	off .. No error on ... An error occurred

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