From 1781a5cfe72c8de4fff66adbd08650014ef526c4 Mon Sep 17 00:00:00 2001
From: Piotr Fusik <fox@scene.pl>
Date: Wed, 23 Jan 2019 00:05:31 +0100
Subject: [PATCH] Optimize the conversions from Atari ASCII to screen codes.

---
 libsrc/atari/cputc.s                  | 22 ++++-----
 libsrc/atari/tgi/atari_tgi_common.inc | 65 ++++++++++++---------------
 2 files changed, 37 insertions(+), 50 deletions(-)

diff --git a/libsrc/atari/cputc.s b/libsrc/atari/cputc.s
index a06daa691..6345983fe 100644
--- a/libsrc/atari/cputc.s
+++ b/libsrc/atari/cputc.s
@@ -1,5 +1,5 @@
 ;
-; Mark Keates, Christian Groessler
+; Mark Keates, Christian Groessler, Piotr Fusik
 ;
 ; void cputcxy (unsigned char x, unsigned char y, char c);
 ; void cputc (char c);
@@ -30,16 +30,13 @@ L4:     cmp     #$0A            ; LF
         cmp     #ATEOL          ; Atari-EOL?
         beq     newline
 
-        tay
-        rol     a
-        rol     a
-        rol     a
-        rol     a
-        and     #3
-        tax
-        tya
-        and     #$9f
-        ora     ataint,x
+        asl     a
+        adc     #$c0
+        bpl     intok
+        eor     #$40
+intok:  lsr
+        bcc     cputdirect
+        eor     #$80
 
 cputdirect:                     ; accepts screen code
         jsr     putchar
@@ -89,6 +86,3 @@ putchar:
         ldy     COLCRS
         sta     (ptr4),y
         jmp     setcursor
-
-        .rodata
-ataint: .byte   64,0,32,96
diff --git a/libsrc/atari/tgi/atari_tgi_common.inc b/libsrc/atari/tgi/atari_tgi_common.inc
index cd486d91b..8c9f6c1f9 100644
--- a/libsrc/atari/tgi/atari_tgi_common.inc
+++ b/libsrc/atari/tgi/atari_tgi_common.inc
@@ -1110,11 +1110,8 @@ skipm:  ; Loop while --dy > 0
 
 ; locals
         string  := tmp1
-        cols    := tmp3
         pixels  := tmp4
         font    := regsave
-.rodata
-        ataint: .byte   64,0,32,96
 .bss
         rows:   .res    1
 
@@ -1222,32 +1219,31 @@ scvert: ldx     x1
 .endif
 
         ; Draw one character
-        ; Convert to ANTIC code
-draw:   tay
-        rol     a
-        rol     a
-        rol     a
-        rol     a
-        and     #3
-        tax
-        tya
-        and     #$9f
-        ora     ataint,x
-        ; Save and clear inverse video bit
-        sta     inv
-        and     #$7F
+draw:
+        ; Extract the inverse mask
+        ldx     #0
+        asl     a
+        bcc     noinv
+        dex
+noinv:  stx     inv
+
         ; Calculate font data address
+        ldx     CHBAS
+        cmp     #$20*2
+        bpl     lowhalf
+        ; Semigraphic or lowercase
+        inx
+        inx
+lowhalf:
+        asl     a
+        bcc     lowquarter
+        ; Letter
+        inx
+lowquarter:
+        asl     a
         sta     font
-        lda     #0
-        sta     font + 1
+        stx     font+1
 
-        .repeat 3
-        asl     font
-        rol     a
-        .endrepeat
-
-        adc     CHBAS
-        sta     font + 1
         ; Save old coords
         bit     text_dir
         bpl     hor
@@ -1273,15 +1269,12 @@ cont:   ldy     #7
         ; Put one row of the glyph
 putrow: sty     rows
         lda     (font),y
-        bit     inv
-        bpl     noinv
-        eor     #$FF
-noinv:  sta     pixels
-        lda     #7
-        sta     cols
+        eor     inv
+        sec
+        rol     a
+        sta     pixels
         ; Put one column of the row
-putcol: asl     pixels
-        bcc     next_col
+putcol: bcc     next_col
         lda     x1
         pha
         lda     x1 + 1
@@ -1317,8 +1310,8 @@ vertinc:
         sub     mag_x
         sta     y2
 L2:
-        dec     cols
-        bpl     putcol
+        asl     pixels
+        bne     putcol
 next_row:
         ; Go to next row
         bit     text_dir