From 25752634387c694e32cbfe5bc5ea6b2559954b0d Mon Sep 17 00:00:00 2001
From: Irmen de Jong <irmen@razorvine.net>
Date: Wed, 28 Apr 2021 02:39:35 +0200
Subject: [PATCH] optimized gfx2.plot() for hires-4c

---
 compiler/res/prog8lib/cx16/gfx2.p8 | 25 ++++++++++++++++++-------
 examples/test.p8                   |  1 -
 2 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/compiler/res/prog8lib/cx16/gfx2.p8 b/compiler/res/prog8lib/cx16/gfx2.p8
index 7b231e38f..3e6a67f2e 100644
--- a/compiler/res/prog8lib/cx16/gfx2.p8
+++ b/compiler/res/prog8lib/cx16/gfx2.p8
@@ -277,9 +277,9 @@ _done
                         ora  colorbits,y
                         sta  cx16.VERA_DATA0
                         cpy  #%00000011         ; next vera byte?
-                        bne  +
+                        bne  +                  ; TODO should be ++?
                         inc  cx16.VERA_ADDR_L
-                        bne  +
+                        bne  +                  ; TODO should be ++?
                         inc  cx16.VERA_ADDR_M
 +                       bne  +
                         inc  cx16.VERA_ADDR_H
@@ -634,13 +634,24 @@ _done
             6 -> {
                 ; highres 4c
                 ; TODO also mostly usable for lores 4c?
-                ; TODO get rid of all the vpoke calls to optimize all plot() ?
                 void addr_mul_24_for_highres_4c(y, x)      ; 24 bits result is in r0 and r1L (highest byte)
+                cx16.r2L = lsb(x) & 3       ; xbits
                 color &= 3
-                color <<= shift4c[lsb(x) & 3]
-                cx16.VERA_ADDR_H &= %00000111   ; no auto advance
-                ubyte value2 = cx16.vpeek(lsb(cx16.r1), cx16.r0) & mask4c[lsb(x) & 3] | color
-                cx16.vpoke(lsb(cx16.r1), cx16.r0, value2)
+                color <<= shift4c[cx16.r2L]
+                %asm {{
+                    stz  cx16.VERA_CTRL
+                    lda  cx16.r1L
+                    sta  cx16.VERA_ADDR_H
+                    lda  cx16.r0H
+                    sta  cx16.VERA_ADDR_M
+                    lda  cx16.r0L
+                    sta  cx16.VERA_ADDR_L
+                    ldy  cx16.r2L           ; xbits
+                    lda  mask4c,y
+                    and  cx16.VERA_DATA0
+                    ora  color
+                    sta  cx16.VERA_DATA0
+                }}
             }
         }
     }
diff --git a/examples/test.p8 b/examples/test.p8
index 0ff4425e6..f732af1fb 100644
--- a/examples/test.p8
+++ b/examples/test.p8
@@ -14,7 +14,6 @@ main {
         ubyte yy
         uword rw
 
-        ; 520 jiffies (hires 4c)
         repeat 20000 {
             rw = rndw()
             yy = (lsb(rw) & 127) + 20