From 3d792603db942c167765db3ba7fc3872b711e018 Mon Sep 17 00:00:00 2001
From: Brion Vibber <brion@pobox.com>
Date: Sat, 11 Mar 2023 20:45:32 -0800
Subject: [PATCH] keyboard nav sorta working

---
 mandel.s | 126 ++++++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 93 insertions(+), 33 deletions(-)

diff --git a/mandel.s b/mandel.s
index 42982cb..97544ec 100644
--- a/mandel.s
+++ b/mandel.s
@@ -87,9 +87,13 @@ SYSVBV = $E45F
 XITVBV = $E462
 SETVBV = $E45C
 
-
-; Keys
-KEY_RIGHT = $07
+; Keycodes!
+KEY_PLUS  = $06
+KEY_MINUS = $0e
+KEY_UP    = $8e
+KEY_DOWN  = $8f
+KEY_LEFT  = $86
+KEY_RIGHT = $87
 
 .struct float48
     exponent .byte
@@ -643,12 +647,12 @@ next:
 
 .endproc
 
-.macro zoom_factor dest, src, zoom, aspect
+.macro scale_zoom dest
+    ; clobbers X, flags
     .local cont
     .local enough
 
     ; cx = (sx << (8 - zoom))
-    copy16 dest, src
     ldx zoom
 cont:
     cpx #8
@@ -657,6 +661,12 @@ cont:
     inx
     jmp cont
 enough:
+.endmacro
+
+.macro zoom_factor dest, src, zoom, aspect
+    ; clobbers A, X, flags, etc
+    copy16 dest, src
+    scale_zoom dest
 
     ; cy = cy * (3 / 4)
     ; cx = cx * (5 / 4)
@@ -803,6 +813,74 @@ done:
     ; draw text
 .endproc
 
+.proc keycheck
+    ; clobbers all
+    ; returns 255 in A if state change or 0 if no change
+
+    ; check keyboard buffer
+    lda CH
+    cmp #$ff
+    beq skip_char
+
+    ; Clear the keyboard buffer and re-enable interrupts
+    ldx #$ff
+    stx CH
+
+    tay
+
+    lda zoom
+    cpy #KEY_PLUS
+    beq plus
+    cpy #KEY_MINUS
+    beq minus
+
+    ; temp = $0010 << (8 - zoom)
+    lda #$10
+    sta temp
+    lda #$00
+    sta temp + 1
+    scale_zoom temp
+
+    cpy #KEY_UP
+    beq up
+    cpy #KEY_DOWN
+    beq down
+    cpy #KEY_LEFT
+    beq left
+    cpy #KEY_RIGHT
+    beq right
+
+skip_char:
+    lda #0
+    rts
+
+plus:
+    cmp #8
+    bpl skip_char
+    inc zoom
+    jmp done
+minus:
+    cmp #1
+    bmi skip_char
+    dec zoom
+    jmp done
+up:
+    sub16 oy, oy, temp 
+    jmp done
+down:
+    add16 oy, oy, temp
+    jmp done
+left:
+    sub16 ox, ox, temp
+    jmp done
+right:
+    add16 ox, ox, temp
+done:
+    lda #255
+    rts
+
+.endproc
+
 .proc start
 
     ; ox = 0; oy = 0; zoom = 0
@@ -896,38 +974,17 @@ loop_sy:
 
 loop_sx:
     zoom_factor cx, sx, zoom, aspect_x
+    add16 cx, cx, ox
     zoom_factor cy, sy, zoom, aspect_y
+    add16 cy, cy, oy
     jsr mandelbrot
     jsr pset
 
-    ; check keyboard buffer
-    lda CH
-    cmp #$ff
-    beq skip_char
-
-    ; Clear the keyboard buffer and re-enable interrupts
-    ldx #$ff
-    stx CH
-
-    tax
-    lsr a
-    lsr a
-    lsr a
-    lsr a
-    tay
-    lda hex_chars,y
-    sta temp
-
-    txa
-    and #$0f
-    tay
-    lda hex_chars,y
-    sta temp + 1
-
-    draw_text 14, 2, temp
-
-skip_char:
+    jsr keycheck
+    beq no_key
+    jmp main_loop
 
+no_key:
     ; check if we should update the counters
     ;
     ; count_pixels >= width? update!
@@ -1039,5 +1096,8 @@ loop_sy_done:
 
 loop:
     ; finished
-    jmp loop
+    jsr keycheck
+    beq loop
+    jmp main_loop
+
 .endproc