1 files changed, 31 insertions, 26 deletions
diff --git a/render.s b/render.s
index 867003e..2faf755 100644
--- a/render.s
+++ b/render.s
@@ -1,11 +1,24 @@
 ;;; Subroutine: render
 ;;; Convert 1px per byte array at pixarray to packed 8px/byte at screen.
-; pixarray is 170x170. screen is 256x170 (TODO: fix display list).
+; pixarray is 170x170. screen is 256x170.
 ; each screen line is: 43 blank px, 170 graphics px, 43 blank.
+
+; This is slow. It takes around 40 jiffies (0.6 sec). However, it only
+; happens once per generate. So not worth optimizing, really.
+
  screenbyte = FR0
  colcount = FR0+1
 
+; RENDER_PROFILE = 1
+
 render:
+.ifdef RENDER_PROFILE
+ lda RTCLOK+1
+ sta $0600
+ lda RTCLOK+2
+ sta $0601
+.endif
+
  lda #<screen
  sta screenptr
  lda #>screen
@@ -16,26 +29,11 @@ render:
  sta pixptr+1
 
  ldx #0
-rline:
+rline_loop:
  lda #0
  sta colcount
  sta screenbyte
 
-; ; clear 40px on left
-; ldy #4
-;lclr:
-; sta (screenptr),y
-; dey
-; bpl lclr
-;
-; ; clear 40px on right
-; ldy #$1b
-;rclr:
-; sta (screenptr),y
-; iny
-; cpy #$20
-; bne rclr
-
 ; clear whole line. this is why pixarray is offset from screen by
 ; one screen line.
  ldy #$1f
@@ -44,13 +42,13 @@ rclr:
  dey
  bpl rclr
 
- ; first pixels start at column 40, plus...
+ ; first pixels start at column 40 (5 bytes in)...
  lda #5
  sta screenbyte
- lda #$10 ; ...mask starts out 0001000, 3 more blank px on left
+ lda #$10 ; ...plus, mask starts out 0001000, 3 more columns to the right.
  sta pixmask
 
-rpix:
+rpix_loop:
  ldy colcount ; ranges 0 to 169
  lda (pixptr),y
  beq notset     ; 0 = not set, non-zero = set
@@ -60,18 +58,19 @@ rpix:
  ora pixmask
  sta (screenptr),y
 notset:
+
  ; pixmask >>= 1; if(pixmask == 0) { pixmask = 0x80; screenbyte++; }
  lsr pixmask
- bne pmok
- ;ror pixmask
- lda #$80
- sta pixmask
+ bcc pmok
+ ror pixmask
  inc screenbyte
 pmok:
+
  inc colcount
  lda colcount
  cmp #$aa
- bne rpix
+ bne rpix_loop
+
  ; pixptr += 0xaa;
  clc
  adc pixptr
@@ -89,6 +88,12 @@ pmok:
  sta screenptr+1
  inx
  cpx #$aa ; hit last line yet?
- bne rline ; if not, go render next line.
+ bne rline_loop ; if not, go render next line.
 
+.ifdef RENDER_PROFILE
+ lda RTCLOK+1
+ sta $0602
+ lda RTCLOK+2
+ sta $0603
+.endif
  rts