optimized gfx2.text() for hires 4c mode

compiler/res/prog8lib/cx16/gfx2.p8

@@ -1112,26 +1112,61 @@ skip:
                 ; hires 4c
                 ; we're going to use a few cx16 registers to make sure every variable is in zeropage in the inner loop.
                 cx16.r11L = color
-                cx16.r8 = y
                 while @(sctextptr) {
                     chardataptr = charset_addr + (@(sctextptr) as uword)*8
                     cx16.vaddr(charset_bank, chardataptr, 1, true)  ; for reading the chardata from Vera data channel 1
+                    position(x, y)              ; only calculated once, we update vera address in the loop instead
+                    cx16.VERA_ADDR_H &= $0f     ; no auto increment
                     repeat 8 {
-                        ; TODO rewrite this in assembly, don't call plot for every pixel
+                        cx16.r10L = cx16.VERA_DATA1  ; get the next 8 horizontal character bits
-                        ;      requires expanding the charbits to 2-bits per pixel (based on color)
-                        ;      also it's way more efficient to draw whole horizontal spans instead of per-character
-                        cx16.r9L = cx16.VERA_DATA1  ; get the next 8 horizontal character bits
                         cx16.r7 = x
                         repeat 8 {
-                            cx16.r9L <<= 1
+                            cx16.r10L <<= 1
-                            if_cs
+                            if_cs {
-                                plot(cx16.r7, cx16.r8, cx16.r11L)
+                                cx16.r2L = cx16.r7L & 3       ; xbits
+                                when cx16.r11L & 3 {
+                                    1 -> cx16.r12L = gfx2.plot.shiftedleft_4c_1[cx16.r2L]
+                                    2 -> cx16.r12L = gfx2.plot.shiftedleft_4c_2[cx16.r2L]
+                                    3 -> cx16.r12L = gfx2.plot.shiftedleft_4c_3[cx16.r2L]
+                                    else -> cx16.r12L = 0
+                                }
+                                cx16.VERA_DATA0 = cx16.VERA_DATA0 & gfx2.plot.mask4c[cx16.r2L] | cx16.r12L
+                            }
                             cx16.r7++
+                            if (cx16.r7 & 3) == 0 {
+                                ; increment the pixel address by one
+                                %asm {{
+                                    stz  cx16.VERA_CTRL
+                                    clc
+                                    lda  cx16.VERA_ADDR_L
+                                    adc  #1
+                                    sta  cx16.VERA_ADDR_L
+                                    lda  cx16.VERA_ADDR_M
+                                    adc  #0
+                                    sta  cx16.VERA_ADDR_M
+                                    lda  cx16.VERA_ADDR_H
+                                    adc  #0
+                                    sta  cx16.VERA_ADDR_H
+                                }}
+                            }
                         }
-                        cx16.r8++
+
+                        ; increment pixel address to the next line
+                        %asm {{
+                            stz  cx16.VERA_CTRL
+                            clc
+                            lda  cx16.VERA_ADDR_L
+                            adc  #(640-8)/4
+                            sta  cx16.VERA_ADDR_L
+                            lda  cx16.VERA_ADDR_M
+                            adc  #0
+                            sta  cx16.VERA_ADDR_M
+                            lda  cx16.VERA_ADDR_H
+                            adc  #0
+                            sta  cx16.VERA_ADDR_H
+                        }}
                     }
                     x+=8
-                    cx16.r8-=8
                     sctextptr++
                 }
             }

docs/source/todo.rst

@@ -47,7 +47,6 @@ Libraries:
 - fix the problems in atari target, and flesh out its libraries.
 - c128 target: make syslib more complete (missing kernal routines)?
 - c64: make the graphics.BITMAP_ADDRESS configurable (VIC banking)
-- optimize several inner loops in gfx2 even further?
 - actually implement modes 3 and perhaps even 2 to gfx2 (lores 16 color and 4 color)
 
 
@@ -75,15 +74,8 @@ STRUCTS again?
 What if we were to re-introduce Structs in prog8? Some thoughts:
 
 - can contain only numeric types (byte,word,float) - no nested structs, no reference types (strings, arrays) inside structs
-- is just some syntactic sugar for a scoped set of variables -> ast transform to do exactly this before codegen. Codegen doesn't know about struct.
+- only as a reference type (uword pointer). This removes a lot of the problems related to introducing a variable length value type.
-- no arrays of struct -- because too slow on 6502 to access those, rather use struct of arrays instead.
+- arrays of struct is just an array of uword pointers. Can even be @split?
-  can we make this a compiler/codegen only issue? i.e. syntax is just as if it was an array of structs?
+- need to introduce typed pointer datatype in prog8
-  or make it explicit in the syntax so that it is clear what the memory layout of it is.
+- str is then syntactic sugar for pointer to character/byte?
-- ability to assign struct variable to another?   this is slow but can be quite handy sometimes.
+- arrays are then syntactic sugar for pointer to byte/word/float?
-  however how to handle this in a function that gets the struct passed as reference? Don't allow it there? (there's no pointer dereferencing concept in prog8)
-- ability to be passed as argument to a function (by reference)?
-  however there is no typed pointer in prog8 at the moment so this can't be implemented in a meaningful way yet,
-  because there is no way to reference it as the struct type again. (current ast gets the by-reference parameter
-  type replaced by uword)
-  So-- maybe don't replace the parameter type in the ast?  Should fix that for str and array types as well then
-

examples/cx16/amiga.p8

@@ -175,7 +175,7 @@ widget {
         const ubyte height = 11
         widget.highlightedrect(x+widget.window_close_icon.width, y, width-64, height, true, active)
         gfx2.plot(x+widget.window_close_icon.width, y+height-1, 1) ; correct bottom left corner
-        gfx2.text(x+32, y+1, 1, titlestr)
+        gfx2.text(x+26, y+1, 1, titlestr)
         widget.window_close_icon(x, y, active)
         widget.window_order_icon(x+width-22, y, active)
         widget.window_flipsize_icon(x+width-44, y, active)

examples/test.p8

@@ -1,20 +1,27 @@
 %import gfx2
-
+%import textio
 
 main {
     sub start() {
-        gfx2.screen_mode(1)         ; 1 and 5 are lo-res and hi-res monochrome
+        gfx2.screen_mode(6)         ; 1 and 5 are lo-res and hi-res monochrome
 
         uword xx
         gfx2.rect(10, 10, 180, 140, 3)
         gfx2.rect(12, 12, 180, 140, 3)
+
+        cbm.SETTIM(0,0,0)
+
         for xx in 5 to 100 {
             gfx2.text(xx, xx, 1, sc:"hello world! should be pixel-aligned.")
-            sys.waitvsync()
+            gfx2.text(xx, xx, 2, sc:"hello world! should be pixel-aligned.")
-            sys.waitvsync()
+            gfx2.text(xx, xx, 3, sc:"hello world! should be pixel-aligned.")
             gfx2.text(xx, xx, 0, sc:"hello world! should be pixel-aligned.")
         }
 
+        gfx2.screen_mode(0)
+        txt.print_uw(cbm.RDTIM16())
+        txt.print(" jiffies")
+
         repeat { }
 	}
 }