add `euclDiv` and `euclMod` to `math` (#16414)

* add `euclDiv` and `euclMod` to `math`
* use abs
* Update lib/pure/math.nim

Co-authored-by: Clyybber <darkmine956@gmail.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/lib/pure/math.nim b/lib/pure/math.nim
index c05e47545..5b19a8ec0 100644
--- a/lib/pure/math.nim
+++ b/lib/pure/math.nim
@@ -882,6 +882,32 @@ func floorMod*[T: SomeNumber](x, y: T): T =
   result = x mod y
   if (result > 0 and y < 0) or (result < 0 and y > 0): result += y
 
+func euclDiv*[T: SomeInteger](x, y: T): T {.since: (1, 5, 1).} =
+  ## Returns euclidean division of `x` by `y`.
+  runnableExamples:
+    assert euclDiv(13, 3) == 4
+    assert euclDiv(-13, 3) == -5
+    assert euclDiv(13, -3) == -4
+    assert euclDiv(-13, -3) == 5
+  result = x div y
+  if x mod y < 0:
+    if y > 0:
+      dec result
+    else:
+      inc result
+
+func euclMod*[T: SomeNumber](x, y: T): T {.since: (1, 5, 1).} =
+  ## Returns euclidean modulo of `x` by `y`.
+  ## `euclMod(x, y)` is non-negative.
+  runnableExamples:
+    assert euclMod(13, 3) == 1
+    assert euclMod(-13, 3) == 2
+    assert euclMod(13, -3) == 1
+    assert euclMod(-13, -3) == 2
+  result = x mod y
+  if result < 0:
+    result += abs(y)
+
 when not defined(js):
   func c_frexp*(x: float32, exponent: var int32): float32 {.
       importc: "frexp", header: "<math.h>".}