Optimize text screen saving lib for space

a2stuff · Dec 26, 2024 · b82b9f2 · b82b9f2
1 parent 5d54e40
commit b82b9f2
Showing 1 changed file with 57 additions and 26 deletions.
diff --git a/lib/save_textpage.s b/lib/save_textpage.s
@@ -5,25 +5,36 @@
 ;;; might trash the text page (e.g. initializing SSC)
 ;;; ============================================================
 
+.scope
+
+        ptr_screen := $06
+        ptr_aux_buf := $08
+        ptr_main_buf := $10
+
+        kNumSegments = 8
+        kSegmentWidth   = $78
+        kSegmentStride  = $80
+
 ;;; Saves text page (except screen holes)
 .proc SaveTextPage
         lda     RD80STORE
         pha
         sta     SET80STORE
 
-        ldx     #0
-loop:
-        .repeat 8, i
-        sta     PAGE2ON
-        lda     $400 + (i*$80),x
-        sta     _textpage_aux_buf + (i*$78),x
+        jsr     InitPointers
+        ldx     #kNumSegments-1
+loop1:  ldy     #kSegmentWidth-1
+loop2:  sta     PAGE2ON
+        lda     (ptr_screen),y
+        sta     (ptr_aux_buf),y
         sta     PAGE2OFF
-        lda     $400 + (i*$80),x
-        sta     _textpage_main_buf + (i*$78),x
-        .endrepeat
-        inx
-        cpx     #$78
-        jne     loop
+        lda     (ptr_screen),y
+        sta     (ptr_main_buf),y
+        dey
+        bpl     loop2
+        jsr     IncPointers
+        dex
+        bpl     loop1
 
         pla
         bmi     :+
@@ -37,25 +48,45 @@ loop:
         pha
         sta     SET80STORE
 
-        ldx     #0
-loop:
-        .repeat 8, i
-        sta     PAGE2ON
-        lda     _textpage_aux_buf + (i*$78),x
-        sta     $400 + (i*$80),x
+        jsr     InitPointers
+        ldx     #kNumSegments-1
+loop1:  ldy     #kSegmentWidth-1
+loop2:  sta     PAGE2ON
+        lda     (ptr_aux_buf),y
+        sta     (ptr_screen),y
         sta     PAGE2OFF
-        lda     _textpage_main_buf + (i*$78),x
-        sta     $400 + (i*$80),x
-        .endrepeat
-        inx
-        cpx     #$78
-        jne     loop
+        lda     (ptr_main_buf),y
+        sta     (ptr_screen),y
+        dey
+        bpl     loop2
+        jsr     IncPointers
+        dex
+        bpl     loop1
 
         pla
         bmi     :+
         sta     CLR80STORE
 :       rts
 .endproc
 
-_textpage_main_buf:      .res    40*24
-_textpage_aux_buf:       .res    40*24
+.proc InitPointers
+        copy16  #$400, ptr_screen
+        copy16  #textpage_aux_buf, ptr_aux_buf
+        copy16  #textpage_main_buf, ptr_main_buf
+        rts
+.endproc
+
+.proc IncPointers
+        add16_8 ptr_screen, #kSegmentStride
+        add16_8 ptr_aux_buf, #kSegmentWidth
+        add16_8 ptr_main_buf, #kSegmentWidth
+        rts
+.endproc
+
+textpage_main_buf:      .res    24*40
+textpage_aux_buf:       .res    24*40
+
+;;; Exports
+::SaveTextPage := SaveTextPage
+::RestoreTextPage := RestoreTextPage
+.endscope