+#define FOG_STAGE_DATA(stage) ((struct fog_stage_data *)stage->privatePtr)
+
+#define FOG_EXP_TABLE_SIZE 256
+#define FOG_MAX (10.0)
+#define EXP_FOG_MAX .0006595
+#define FOG_INCR (FOG_MAX/FOG_EXP_TABLE_SIZE)
+static GLfloat exp_table[FOG_EXP_TABLE_SIZE];
+static GLfloat inited = 0;
+
+#if 1
+#define NEG_EXP( result, narg ) \
+do { \
+ GLfloat f = (GLfloat) (narg * (1.0/FOG_INCR)); \
+ GLint k = (GLint) f; \
+ if (k > FOG_EXP_TABLE_SIZE-2) \
+ result = (GLfloat) EXP_FOG_MAX; \
+ else \
+ result = exp_table[k] + (f-k)*(exp_table[k+1]-exp_table[k]); \
+} while (0)
+#else
+#define NEG_EXP( result, narg ) \
+do { \
+ result = exp(-narg); \
+} while (0)
+#endif
+
+
+/**
+ * Initialize the exp_table[] lookup table for approximating exp().
+ */
+static void
+init_static_data( void )
+{
+ GLfloat f = 0.0F;
+ GLint i = 0;
+ for ( ; i < FOG_EXP_TABLE_SIZE ; i++, f += FOG_INCR) {
+ exp_table[i] = EXPF(-f);
+ }
+ inited = 1;
+}