make NEG update flags correctly (oops).

also misc graphics notes added.

ARMInterpreter_ALU.cpp

@@ -1301,8 +1301,10 @@ void T_NEG_REG(ARM* cpu)
     u32 b = cpu->R[(cpu->CurInstr >> 3) & 0x7];
     u32 res = -b;
     cpu->R[cpu->CurInstr & 0x7] = res;
-    cpu->SetNZ(res & 0x80000000,
-               !res);
+    cpu->SetNZCV(res & 0x80000000,
+                 !res,
+                 CARRY_SUB(0, b),
+                 OVERFLOW_SUB(0, b, res));
 }
 
 void T_CMP_REG(ARM* cpu)

GPU2D.cpp

@@ -54,7 +54,8 @@
 //
 // 3D/2D blending rules
 // * if destination selected as 2nd target:
-//   blending is applied instead of the selected color effect, using full 31bit alpha from 3D layer
+//   blending is applied instead of the selected color effect, using full 5bit alpha from 3D layer
+//   (or 6bit alpha? TODO: check it)
 //   this even if the selected color effect is 'none'.
 //   apparently this works even if BG0 isn't selected as 1st target
 // * if BG0 is selected as 1st target, destination not selected as 2nd target:
@@ -231,7 +232,7 @@ void GPU2D::Write16(u32 addr, u16 val)
         EVB = (val >> 8) & 0x1F;
         if (EVB > 16) EVB = 16;
         return;
-    case 0x54:
+    case 0x054:
         EVY = val & 0x1F;
         if (EVY > 16) EVY = 16;
         return;

GPU3D.cpp

@@ -44,11 +44,12 @@
 //   the added bias affects interpolation.
 //
 // depth buffer:
-// Z-buffering mode: val = ((Z * 0x800 * 0x1000) / W) + 0x7FFCFF
-// W-buffering mode: val = W - 0x1FF
-// TODO: confirm W, because it's weird
-// ... nope, that shit above isn't right
-// also, the formula for the clear depth on GBAtek appears to be wrong
+// Z-buffering mode: val = ((Z * 0x800 * 0x1000) / W) + 0x7FFEFF
+// W-buffering mode: val = W
+//
+// formula for clear depth: (GBAtek is wrong there)
+// clearZ = (val * 0x200) + 0x1FF;
+// if (clearZ >= 0x010000 && clearZ < 0xFFFFFF) clearZ++;
 
 
 namespace GPU3D