Avoid duplication of code

Instead jump to the middle of the while loop to reuse the error
correction code.

1 files changed, 4 insertions, 25 deletions

diff --git a/dda.c b/dda.c
index 5c8a3a1..00fa404 100644
--- a/dda.c
+++ b/dda.c
@@ -74,33 +74,12 @@ dda (test_data_t *testdata)
     double xi = next_sample_x (x0);
     double e = (xi - x0) * dy - (yi - y0) * dx;
 
-    if (dx >= 0)
-    {
-	while (e <= 0)
-	{
-	    double s = sample_step_x_forward (xi);
-
-	    e += s * dy;
-	    xi += s;
-	}
-    }
-    else
-    {
-	double s = sample_step_x_backward (xi);
-
-	while (e > s * dy)
-	{
-	    e -= s * dy;
-	    xi -= s;
-
-	    s = sample_step_x_backward (xi);
-	}
-    }
-
 #if 0
     printf ("= = = = %f %f %f %f = = = = \n", x0, y0, x1, y1);
 #endif
 
+    goto step;
+
     while (yi < next_sample_y (y1))
     {
 	if (testdata->points[i++] != xi		||
@@ -111,7 +90,9 @@ dda (test_data_t *testdata)
 	}
 
 	e -= sample_step_y (yi) * dx;
+	yi += sample_step_y (yi);
 
+    step:
 	if (dx >= 0)
 	{
 	    while (e <= 0)
@@ -134,8 +115,6 @@ dda (test_data_t *testdata)
 		s = sample_step_x_backward (xi);
 	    }
 	}
-
-	yi += sample_step_y (yi);
     }
 }