1 files changed, 62 insertions, 0 deletions
diff --git a/sprite.c b/sprite.c
new file mode 100644
index 000000000..f0a130d4e
--- /dev/null
+++ b/sprite.c
@@ -0,0 +1,62 @@
+#include "stdafx.h"
+
+#include <stdarg.h>
+
+#include "ttd.h"
+#include "sprite.h"
+
+
+struct SpriteGroup *EvalDeterministicSpriteGroup(struct DeterministicSpriteGroup *dsg, int value)
+{
+	int i;
+
+	value >>= dsg->shift_num; // This should bring us to the byte range.
+	value &= dsg->and_mask;
+
+	if (dsg->operation != DSG_OP_NONE)
+		value += (signed char) dsg->add_val;
+
+	switch (dsg->operation) {
+		case DSG_OP_DIV:
+			value /= (signed char) dsg->divmod_val;
+			break;
+		case DSG_OP_MOD:
+			value %= (signed char) dsg->divmod_val;
+			break;
+		case DSG_OP_NONE:
+			break;
+	}
+
+	for (i = 0; i < dsg->num_ranges; i++) {
+		struct DeterministicSpriteGroupRange *range = &dsg->ranges[i];
+
+		if (range->low <= value && value <= range->high)
+			return &range->group;
+	}
+
+	return dsg->default_group;
+}
+
+int GetDeterministicSpriteValue(byte var)
+{
+	switch (var) {
+		case 0x00:
+			return _date;
+		case 0x01:
+			return _cur_year;
+		case 0x02:
+			return _cur_month;
+		case 0x03:
+			return _opt.landscape;
+		case 0x09:
+			return _date_fract;
+		case 0x0A:
+			return _tick_counter;
+		case 0x0C:
+			/* If we got here, it means there was no callback or
+			 * callbacks aren't supported on our callpath. */
+			return 0;
+		default:
+			return -1;
+	}
+}