DIV and MOD with negative operands
Posted: Sat Nov 15, 2014 6:46 am
The behaviour of DIV and MOD operators with negative operands in Astrobe for Cortex-M3/M4 did not conform to the Oberon language report in v5.1 and earlier versions. This has been fixed in v5.2 of both products.
The Oberon language report defines DIV and MOD as follows:
Constants:
Variables:
Note that due to precedence rules, the following are identical statements:
Also:
The Oberon language report defines DIV and MOD as follows:
The following are examples of the new conforming behaviour:The operators DIV and MOD apply to integer operands only. Let q = x DIV y, and r = x MOD y.
Then quotient q and remainder r are defined by the equation
Code: Select all
x = q*y + r 0 <= r < y
Constants:
Code: Select all
q := 10 DIV -3; (* Compile Error: divisor must be > 0 *)
r := 10 MOD -3; (* Compile Error: modulus must be > 0 *)
q := (-10) DIV 3; (* q = -4 *)
r := (-10) MOD 3; (* r = 2 *)Code: Select all
x := 10;
y := -3;
q := x DIV y; (* Runtime Error 7 *)
r := x MOD y; (* Runtime Error 7 *)
Code: Select all
q := -10 DIV 3; (* q = -3 *)
q := -(10 DIV 3); (* q = -3 *)
Code: Select all
r := -10 MOD 3; (* r = -1 *)
r := -(10 MOD 3); (* r = -1 *)