Small optimizations to some format conversion routines.

resources/format_conversions.txt

@@ -36,9 +36,10 @@ u8->s32 {
 }
 
 # r = (x / 255) * 2 - 1
+#   = (x / 127.5) - 1
+#   = (x * 0.00784313725490196078) - 1
 u8->f32 {
-    div r x 255.0f;
-    mul r r 2;
+    mul r x 0.00784313725490196078f;
     sub r r 1;
 }
 
@@ -60,11 +61,12 @@ s16->s32 {
     shl r x 16;
 }
 
-# r = ((x + 32768) / 65536) * 2 - 1
+# r = ((x + 32768) / 65535) * 2 - 1
+#   = (x + 32768) / 32767.5) - 1
+#   = (x + 32768) * 0.00003051804379339284) - 1
 s16->f32 {
-    add r x 32768.0f;
-    div r r 65536.0f;
-    mul r r 2;
+    add (flt)r x 32768;
+    mul r r 0.00003051804379339284f;
     sub r r 1;
 }
 
@@ -87,10 +89,11 @@ s24->s32 {
 }
 
 # r = ((x + 8388608) / 16777215) * 2 - 1
+#   = (x + 8388608) / 8388607.5) - 1
+#   = (x + 8388608) * 0.00000011920929665621) - 1
 s24->f32 {
-    add r x 8388608.0f;
-    div r r 16777215.0f;
-    mul r r 2;
+    add (flt)r x 8388608;
+    mul r r 0.00000011920929665621f;
     sub r r 1;
 }