initial commits

inversescale.go

@@ -0,0 +1,15 @@
+package imgrow
+
+// inverseScale basically does:
+//
+//	return n / scalar
+//
+// ... except, that it deals with the case where 0 == scalar in a special way.
+func inverseScale(scalar int, n int) int {
+	switch {
+	case 0 == scalar:
+		return divideByZero(n)
+	default:
+		return n / scalar
+	}
+}

inversescale_test.go

@@ -0,0 +1,379 @@
+package imgrow
+
+import (
+	"testing"
+)
+
+func TestInverseScale(t *testing.T) {
+
+	tests := []struct{
+		Scalar int
+		N int
+		Expected int
+	}{
+		{
+			Scalar: 0,
+			N: -8,
+			Expected: intMin,
+		},
+		{
+			Scalar: 0,
+			N: -7,
+			Expected: intMin,
+		},
+		{
+			Scalar: 0,
+			N: -6,
+			Expected: intMin,
+		},
+		{
+			Scalar: 0,
+			N: -5,
+			Expected: intMin,
+		},
+		{
+			Scalar: 0,
+			N: -4,
+			Expected: intMin,
+		},
+		{
+			Scalar: 0,
+			N: -3,
+			Expected: intMin,
+		},
+		{
+			Scalar: 0,
+			N: -2,
+			Expected: intMin,
+		},
+		{
+			Scalar: 0,
+			N: -1,
+			Expected: intMin,
+		},
+		{
+			Scalar: 0,
+			N: 0,
+			Expected: 0,
+		},
+		{
+			Scalar: 0,
+			N: 1,
+			Expected: intMax,
+		},
+		{
+			Scalar: 0,
+			N: 2,
+			Expected: intMax,
+		},
+		{
+			Scalar: 0,
+			N: 3,
+			Expected: intMax,
+		},
+		{
+			Scalar: 0,
+			N: 4,
+			Expected: intMax,
+		},
+		{
+			Scalar: 0,
+			N: 5,
+			Expected: intMax,
+		},
+		{
+			Scalar: 0,
+			N: 6,
+			Expected: intMax,
+		},
+		{
+			Scalar: 0,
+			N: 7,
+			Expected: intMax,
+		},
+		{
+			Scalar: 0,
+			N: 8,
+			Expected: intMax,
+		},
+
+
+
+		{
+			Scalar: 1,
+			N: -8,
+			Expected: -8,
+		},
+		{
+			Scalar: 1,
+			N: -7,
+			Expected: -7,
+		},
+		{
+			Scalar: 1,
+			N: -6,
+			Expected: -6,
+		},
+		{
+			Scalar: 1,
+			N: -5,
+			Expected: -5,
+		},
+		{
+			Scalar: 1,
+			N: -4,
+			Expected: -4,
+		},
+		{
+			Scalar: 1,
+			N: -3,
+			Expected: -3,
+		},
+		{
+			Scalar: 1,
+			N: -2,
+			Expected: -2,
+		},
+		{
+			Scalar: 1,
+			N: -1,
+			Expected: -1,
+		},
+		{
+			Scalar: 1,
+			N: 0,
+			Expected: 0,
+		},
+		{
+			Scalar: 1,
+			N: 1,
+			Expected: 1,
+		},
+		{
+			Scalar: 1,
+			N: 2,
+			Expected: 2,
+		},
+		{
+			Scalar: 1,
+			N: 3,
+			Expected: 3,
+		},
+		{
+			Scalar: 1,
+			N: 4,
+			Expected: 4,
+		},
+		{
+			Scalar: 1,
+			N: 5,
+			Expected: 5,
+		},
+		{
+			Scalar: 1,
+			N: 6,
+			Expected: 6,
+		},
+		{
+			Scalar: 1,
+			N: 7,
+			Expected: 7,
+		},
+		{
+			Scalar: 1,
+			N: 8,
+			Expected: 8,
+		},
+
+
+
+		{
+			Scalar: 2,
+			N: -8,
+			Expected: -4,
+		},
+		{
+			Scalar: 2,
+			N: -7,
+			Expected: -3,
+		},
+		{
+			Scalar: 2,
+			N: -6,
+			Expected: -3,
+		},
+		{
+			Scalar: 2,
+			N: -5,
+			Expected: -2,
+		},
+		{
+			Scalar: 2,
+			N: -4,
+			Expected: -2,
+		},
+		{
+			Scalar: 2,
+			N: -3,
+			Expected: -1,
+		},
+		{
+			Scalar: 2,
+			N: -2,
+			Expected: -1,
+		},
+		{
+			Scalar: 2,
+			N: -1,
+			Expected: 0,
+		},
+		{
+			Scalar: 2,
+			N: 0,
+			Expected: 0,
+		},
+		{
+			Scalar: 2,
+			N: 1,
+			Expected: 0,
+		},
+		{
+			Scalar: 2,
+			N: 2,
+			Expected: 1,
+		},
+		{
+			Scalar: 2,
+			N: 3,
+			Expected: 1,
+		},
+		{
+			Scalar: 2,
+			N: 4,
+			Expected: 2,
+		},
+		{
+			Scalar: 2,
+			N: 5,
+			Expected: 2,
+		},
+		{
+			Scalar: 2,
+			N: 6,
+			Expected: 3,
+		},
+		{
+			Scalar: 2,
+			N: 7,
+			Expected: 3,
+		},
+		{
+			Scalar: 2,
+			N: 8,
+			Expected: 4,
+		},
+
+
+
+		{
+			Scalar: 3,
+			N: -8,
+			Expected: -2,
+		},
+		{
+			Scalar: 3,
+			N: -7,
+			Expected: -2,
+		},
+		{
+			Scalar: 3,
+			N: -6,
+			Expected: -2,
+		},
+		{
+			Scalar: 3,
+			N: -5,
+			Expected: -1,
+		},
+		{
+			Scalar: 3,
+			N: -4,
+			Expected: -1,
+		},
+		{
+			Scalar: 3,
+			N: -3,
+			Expected: -1,
+		},
+		{
+			Scalar: 3,
+			N: -2,
+			Expected: 0,
+		},
+		{
+			Scalar: 3,
+			N: -1,
+			Expected: 0,
+		},
+		{
+			Scalar: 3,
+			N: 0,
+			Expected: 0,
+		},
+		{
+			Scalar: 3,
+			N: 1,
+			Expected: 0,
+		},
+		{
+			Scalar: 3,
+			N: 2,
+			Expected: 0,
+		},
+		{
+			Scalar: 3,
+			N: 3,
+			Expected: 1,
+		},
+		{
+			Scalar: 3,
+			N: 4,
+			Expected: 1,
+		},
+		{
+			Scalar: 3,
+			N: 5,
+			Expected: 1,
+		},
+		{
+			Scalar: 3,
+			N: 6,
+			Expected: 2,
+		},
+		{
+			Scalar: 3,
+			N: 7,
+			Expected: 2,
+		},
+		{
+			Scalar: 3,
+			N: 8,
+			Expected: 2,
+		},
+	}
+
+	for testNumber, test := range tests {
+
+		actual := inverseScale(test.Scalar, test.N)
+		expected := test.Expected
+
+		if expected != actual {
+			t.Errorf("For test #%d, the actual value is not what was expected.", testNumber)
+			t.Logf("EXPECTED: %d", expected)
+			t.Logf("ACTUAL:   %d", actual)
+			t.Logf("SCALAR: %d", test.Scalar)
+			t.Logf("N:      %d", test.N)
+			continue
+		}
+	}
+}