Add round() and lround() to proj_math.h

2 files changed, 29 insertions, 0 deletions

diff --git a/src/pj_math.c b/src/pj_math.c
index 751c2750..97d4ae56 100644
--- a/src/pj_math.c
+++ b/src/pj_math.c
@@ -67,5 +67,33 @@ int pj_isnan (double x) {
     return x != x;
 }
 
+double pj_round(double x) {
+  /* The handling of corner cases is copied from boost; see
+   *   https://github.com/boostorg/math/pull/8
+   * with improvements to return -0.0 when appropriate */
+  double t;
+  if (x == 0)
+    return x;               /* Retain sign of 0 */
+  else if (0 < x && x <  0.5)
+    return +0.0;
+  else if (0 > x && x > -0.5)
+    return -0.0;
+  else if (x > 0) {
+    t = ceil(x);
+    return 0.5 < t - x ? t - 1 : t;
+  } else {                  /* Includes NaN */
+    t = floor(x);
+    return 0.5 < x - t ? t + 1 : t;
+  }
+}
+
+long pj_lround(double x) {
+  /* Default value for overflow + NaN + (x == LONG_MIN) */
+  long r = LONG_MIN;
+  x = round(x);
+  if (fabs(x) < -(double)LONG_MIN) /* Assume (double)LONG_MIN is exact */
+    r = (int)x;
+  return r;
+}
 
 #endif /* !(defined(HAVE_C99_MATH) && HAVE_C99_MATH) */
diff --git a/src/proj_math.h b/src/proj_math.h
index 1e0c6217..ca3ab401 100644
--- a/src/proj_math.h
+++ b/src/proj_math.h
@@ -29,6 +29,7 @@
 #define PROJ_MATH_H
 
 #include <math.h>
+#include <limits.h>
 
 #ifdef __cplusplus
 extern "C" {