o cleanup

2009-04-22 20:04:28 +02:00
parent 55e3468f74
commit 0c378a9f7c
1078 changed files with 0 additions and 0 deletions
--- a/tools/bsnes/ppu/bppu/bppu_render_addsub.cpp
+++ b/tools/bsnes/ppu/bppu/bppu_render_addsub.cpp
@@ -0,0 +1,25 @@
+#ifdef BPPU_CPP
+
+//color addition / subtraction
+//thanks go to blargg for the optimized algorithms
+inline uint16 bPPU::addsub(uint32 x, uint32 y, bool halve) {
+  if(!regs.color_mode) {
+    if(!halve) {
+      unsigned sum   = x + y;
+      unsigned carry = (sum - ((x ^ y) & 0x0421)) & 0x8420;
+      return (sum - carry) | (carry - (carry >> 5));
+    } else {
+      return (x + y - ((x ^ y) & 0x0421)) >> 1;
+    }
+  } else {
+    unsigned diff   = x - y + 0x8420;
+    unsigned borrow = (diff - ((x ^ y) & 0x8420)) & 0x8420;
+    if(!halve) {
+      return   (diff - borrow) & (borrow - (borrow >> 5));
+    } else {
+      return (((diff - borrow) & (borrow - (borrow >> 5))) & 0x7bde) >> 1;
+    }
+  }
+}
+
+#endif