extra effects

slide5.asm

@@ -1,16 +1,17 @@
 ; -----------------------------------------------------------
 ; slide5.asm - the assembly confession
+;   the body is typed in live, one character per frame, with a
+;   white block cursor; the closing line appears when the
+;   typing is done and pulses
 ; -----------------------------------------------------------
 
 s5_init:
     jsr clear_screen
     +prtext  3, 11, WHITE, txt_conf1, txt_conf1_end - txt_conf1
-    +prtext  7,  3, LGREY, txt_conf2, txt_conf2_end - txt_conf2
-    +prtext  9,  3, LGREY, txt_conf3, txt_conf3_end - txt_conf3
-    +prtext 12,  3, WHITE, txt_conf4, txt_conf4_end - txt_conf4
-    +prtext 15,  3, LGREY, txt_conf5, txt_conf5_end - txt_conf5
-    +prtext 17,  3, LGREY, txt_conf6, txt_conf6_end - txt_conf6
-    +prtext 21, 11, CYAN,  txt_conf7, txt_conf7_end - txt_conf7
+    lda #0               ; the body starts empty and gets typed in
+    sta t_line
+    sta t_chr
+    sta t_done
     rts
 
 s5_update:
@@ -19,6 +20,9 @@ s5_update:
     bne s5_update
 
     inc framectr
+    lda t_done
+    beq s5_type
+
     lda framectr         ; pulse on the "(the ai says hi.)" line
     lsr
     lsr
@@ -33,6 +37,55 @@ s5_loop:
     bpl s5_loop
     rts
 
+; ---- type one character per frame ----
+s5_type:
+    ldx t_line
+    ldy t_row,x          ; screen/color pointers to the line start
+    lda mul40lo,y
+    clc
+    adc #3               ; body column
+    sta scrlo
+    sta collo
+    lda mul40hi,y
+    adc #>SCREEN         ; carry still clear (row starts stay low)
+    sta scrhi
+    clc
+    adc #$d4
+    sta colhi
+    lda t_txtlo,x
+    sta txtlo
+    lda t_txthi,x
+    sta txthi
+
+    ldy t_chr
+    lda (txtlo),y        ; the character lands where the cursor was
+    sta (scrlo),y
+    lda t_color,x
+    sta (collo),y
+    iny
+    cpy #34              ; all body lines are exactly 34 chars
+    beq s5_nextline
+    sty t_chr
+    lda #$a0             ; block cursor at the next cell
+    sta (scrlo),y
+    lda #WHITE
+    sta (collo),y
+    rts
+
+s5_nextline:
+    lda #0
+    sta t_chr
+    inc t_line
+    lda t_line
+    cmp #5
+    bne s5_ret
+    ; typing done: the closing line appears and starts pulsing
+    +prtext 21, 11, CYAN, txt_conf7, txt_conf7_end - txt_conf7
+    lda #1
+    sta t_done
+s5_ret:
+    rts
+
 ; ---- data ----
 txt_conf1:
     !scr "a quick confession"
@@ -41,19 +94,28 @@ txt_conf1_end:
 ; exactly 34 chars, so both edges line up at columns 3 and 36
 txt_conf2:
     !scr "we speak c/c++, lua, python, java,"
-txt_conf2_end:
 txt_conf3:
     !scr "go,   ruby,  js,  elixir,  pascal."
-txt_conf3_end:
 txt_conf4:
     !scr "but  6502  assembly?  not  a word."
-txt_conf4_end:
 txt_conf5:
     !scr "so   this  slideshow  was  written"
-txt_conf5_end:
 txt_conf6:
     !scr "with  a  little  help  from an ai."
-txt_conf6_end:
 txt_conf7:
     !scr "(the ai says hi.)"
 txt_conf7_end:
+
+t_row:                   ; body line rows
+    !byte 7, 9, 12, 15, 17
+t_color:
+    !byte LGREY, LGREY, WHITE, LGREY, LGREY
+t_txtlo:
+    !byte <txt_conf2, <txt_conf3, <txt_conf4, <txt_conf5, <txt_conf6
+t_txthi:
+    !byte >txt_conf2, >txt_conf3, >txt_conf4, >txt_conf5, >txt_conf6
+
+; ---- variables ----
+t_line:    !byte 0       ; body line being typed (0-4)
+t_chr:     !byte 0       ; next character within the line
+t_done:    !byte 0       ; 1 = typing finished, closing line pulses