Simplify interface to rgbPix match

src/dhgr.tk/utils/dhgrrgb.pla

@@ -56,8 +56,10 @@ def dist(x1, y1, z1, x2, y2, z2)#2
   return xx:[0], xx:[1]
 end
 
-def rgbPix(r0, g0, b0, r1, g1, b1, r2, g2, b2, x)#1
-  var errptr
+def rgbPix(rgbptr, errptr, cx)#1
+  var r0, g0, b0
+  var r1, g1, b1
+  var r2, g2, b2
   var pr1, pg1, pb1
   var pr2, pg2, pb2
   var pr3, pg3, pb3
@@ -65,30 +67,31 @@ def rgbPix(r0, g0, b0, r1, g1, b1, r2, g2, b2, x)#1
   var lr1, lg1, lb1
   var lr2, lg2, lb2
   var er, eg, eb
-  var cr, cg, cb, cx
+  var cr, cg, cb
   byte i
   res[t_i32] pd, d0, d1, d2
 
-  // Error propogation
-  errptr = rgbErr + x * 3 * 2
   // Previous 3/4 chroma cycle
-  i = ((x - 1) & 3) * 3
+  i = ((cx - 1) & 3) * 3
   pr1 = ntscCycle[i+RED]
   pg1 = ntscCycle[i+GRN]
   pb1 = ntscCycle[i+BLU]
-  i = ((x - 2) & 3) * 3
+  i = ((cx - 2) & 3) * 3
   pr2 = pr1 + ntscCycle[i+RED]
   pg2 = pg1 + ntscCycle[i+GRN]
   pb2 = pb1 + ntscCycle[i+BLU]
-  i = ((x - 3) & 3) * 3
+  i = ((cx - 3) & 3) * 3
   pr3 = pr2 + ntscCycle[i+RED]
   pg3 = pg2 + ntscCycle[i+GRN]
   pb3 = pb2 + ntscCycle[i+BLU]
   // Current chroma cycle
-  i = (x & 3) * 3
+  i = cx * 3
   cr = pr3 + ntscChroma[i+RED]
   cg = pg3 + ntscChroma[i+GRN]
   cb = pb3 + ntscChroma[i+BLU]
+  r0 = gamma[rgbptr->RED]]
+  g0 = gamma[rgbptr->GRN]]
+  b0 = gamma[rgbptr->BLU]]
   if errDiv
     r0 = r0 + errptr=>[RED] / errDiv
     g0 = g0 + errptr=>[GRN] / errDiv
@@ -98,10 +101,13 @@ def rgbPix(r0, g0, b0, r1, g1, b1, r2, g2, b2, x)#1
   pd:[0], pd:[1] = dist(r0, g0, b0, pr3, pg3, pb3)
   if lookahead > 0 
     // Look ahead in chroma cycle for possible better match for next RGB pixel
-    i  = ((x + 1) & 3) * 3
+    i  = ((cx + 1) & 3) * 3
     lr1 = pr2 + ntscChroma[i+RED]
     lg1 = pg2 + ntscChroma[i+GRN]
     lb1 = pb2 + ntscChroma[i+BLU]
+    r1 = gamma[rgbptr->[3+RED]]]
+    g1 = gamma[rgbptr->[3+GRN]]]
+    b1 = gamma[rgbptr->[3+BLU]]]
     if errDiv
       r1 = r1 + (errptr=>[3+RED] + r0 - lr1) / errDiv
       g1 = g1 + (errptr=>[3+GRN] + g0 - lg1) / errDiv
@@ -111,14 +117,17 @@ def rgbPix(r0, g0, b0, r1, g1, b1, r2, g2, b2, x)#1
     d1:[0], d1:[1] = dist(r1, g1, b1, lr1, lg1, lb1)
     if lookahead > 1
       // Look ahead in chroma cycle for possible better match for after next RGB pixel
-      i  = ((x + 2) & 3) * 3
+      i  = ((cx + 2) & 3) * 3
       lr2 = pr1 + ntscChroma[i+RED]
       lg2 = pg1 + ntscChroma[i+GRN]
       lb2 = pb1 + ntscChroma[i+BLU]
+      r2 = gamma[rgbptr->[6+RED]]]
+      g2 = gamma[rgbptr->[6+GRN]]]
+      b2 = gamma[rgbptr->[6+BLU]]]
       if errDiv
-        r2 = r2 + (errptr=>[3+RED] + r1 - lr2) / errDiv
-        g2 = g2 + (errptr=>[3+GRN] + g1 - lg2) / errDiv
-        b2 = b2 + (errptr=>[3+BLU] + b1 - lb2) / errDiv
+        r2 = r2 + (errptr=>[6+RED] + r1 - lr2) / errDiv
+        g2 = g2 + (errptr=>[6+GRN] + g1 - lg2) / errDiv
+        b2 = b2 + (errptr=>[6+BLU] + b1 - lb2) / errDiv
       fin
       // Calc match if next pixel is one
       d2:[0], d2:[1] = dist(r2, g2, b2, lr2, lg2, lb2)
@@ -131,7 +140,7 @@ def rgbPix(r0, g0, b0, r1, g1, b1, r2, g2, b2, x)#1
   fin
   // Calc match if current pixel is one
   d0:[0], d0:[1] = dist(r0, g0, b0, cr, cg, cb)
-  i = (x & 3) * 3
+  i = cx * 3
   load32(@d0)
   if islt32(@pd) and islt32(@d1) and islt32(@d2)
     // RGB better matched with current 1/4 chroma color
@@ -194,9 +203,9 @@ def rgbExit#0
 end
 
 def rgbImportExport(rgbfile, dhgrfile)#0
-  byte refnum, r0, g0, b0, r1, g1, b1, r2, g2, b2
+  byte refnum
   var i, j
-  var rgbScanline, rgbptr
+  var rgbScanline, rgbptr, errptr
 
   refnum = fileio:open(rgbfile)
   if refnum
@@ -207,24 +216,14 @@ def rgbImportExport(rgbfile, dhgrfile)#0
       for j = 0 to 191
         fileio:read(refnum, rgbScanline,  560 * 3)
         rgbptr = rgbScanline
-        r1 = gamma[rgbptr->RED]
-        g1 = gamma[rgbptr->GRN]
-        b1 = gamma[rgbptr->BLU]
-        rgbptr = rgbptr + 3
-        r2 = gamma[rgbptr->RED]
-        g2 = gamma[rgbptr->GRN]
-        b2 = gamma[rgbptr->BLU]
+        errptr = rgbErr
         for i = 0 to 559
-          r0, g0, b0 = r1, g1, b1
-          r1, g1, b1 = r2, g2, b2
-          rgbptr = rgbptr + 3
-          r2 = gamma[rgbptr->RED]
-          g2 = gamma[rgbptr->GRN]
-          b2 = gamma[rgbptr->BLU]
-          if rgbPix(r0, g0, b0, r1, g1, b1, r2, g2, b2, i)
+          if rgbPix(rgbptr, errptr, i & 3)
             dhgrSet(i, j)
           fin
-          // Map dark grey to light grey
+          rgbptr = rgbptr + 3
+          errptr = errptr + 3 * 2
+         // Map dark grey to light grey
           if (i & 3) == 3 and dcgrGetPixel(i >> 2, j) == 5
              dhgrOp(OP_SRC)
              dcgrColor(10)