From 100c0f33148c411a6bb066f0de32e1f79ffe2c78 Mon Sep 17 00:00:00 2001
From: Brooke Vibber <bvibber@pobox.com>
Date: Mon, 30 Dec 2024 09:16:08 -0800
Subject: [PATCH] 1/2/3 selectable viewports

---
 mandel.s | 65 ++++++++++++++++++++++++++++++++++++++++++--------------
 todo.md  |  2 --
 2 files changed, 49 insertions(+), 18 deletions(-)

diff --git a/mandel.s b/mandel.s
index 0239167..90396d4 100644
--- a/mandel.s
+++ b/mandel.s
@@ -104,6 +104,9 @@ KEY_UP    = $8e
 KEY_DOWN  = $8f
 KEY_LEFT  = $86
 KEY_RIGHT = $87
+KEY_1     = $1f
+KEY_2     = $1e
+KEY_3     = $1a
 
 .struct float48
     exponent .byte
@@ -250,14 +253,17 @@ fill_masks:
 
 viewport_zoom:
     .byte 1
+    .byte 6
     .byte 8
 
 viewport_ox:
     .word $0000
     .word $f110
+    .word $f110
 
 viewport_oy:
     .word $0000
+    .word $fb60
     .word $fbe0
 
 ; 2 + 9 * byte cycles
@@ -1206,7 +1212,13 @@ done:
     beq left
     cpy #KEY_RIGHT
     beq right
-
+    cpy #KEY_1
+    beq one
+    cpy #KEY_2
+    beq two
+    cpy #KEY_3
+    beq three
+ 
 skip_char:
     lda #0
     rts
@@ -1234,6 +1246,19 @@ left:
     jmp done
 right:
     add16 ox, ox, temp
+    jmp done
+one:
+    ldx #0
+    jmp load_key_viewport
+two:
+    ldx #1
+    jmp load_key_viewport
+three:
+    ldx #2
+    ; fall through
+load_key_viewport:
+    jsr load_viewport
+    ; fall through
 done:
     lda #255
     rts
@@ -1271,13 +1296,10 @@ zero_byte_loop:
     rts
 .endproc
 
-.proc start
+; input: viewport selector in x
+; clobbers: a, x
+.proc load_viewport
 
-    jsr imul8xe_init
-
-    ; initialize viewport
-    ldx #0 ; overview
-    ;ldx #1 ; closeup
     lda viewport_zoom,x
     sta zoom
 
@@ -1294,16 +1316,16 @@ zero_byte_loop:
     lda viewport_oy,x
     sta oy + 1
 
-    ; count_frames = 0; count_pixels = 0
-    lda #0
-    sta count_frames
-    sta count_pixels
+    rts
+.endproc
 
-    ; total_ms = 0.0; total_pixels = 0.0
-    ldx #total_ms
-    jsr ZF1
-    ldx #total_pixels
-    jsr ZF1
+.proc start
+
+    jsr imul8xe_init
+
+    ; initialize viewport
+    ldx #0 ; overview
+    jsr load_viewport
 
     ; Disable display DMA
     lda #0
@@ -1345,6 +1367,17 @@ copy_byte_loop:
     jsr SETVBV
 
 main_loop:
+    ; count_frames = 0; count_pixels = 0
+    lda #0
+    sta count_frames
+    sta count_pixels
+
+    ; total_ms = 0.0; total_pixels = 0.0
+    ldx #total_ms
+    jsr ZF1
+    ldx #total_pixels
+    jsr ZF1
+
     jsr clear_screen
     jsr status_bar
 
diff --git a/todo.md b/todo.md
index 2e28c8e..6c6d84d 100644
--- a/todo.md
+++ b/todo.md
@@ -1,7 +1,5 @@
 things to try:
 
-* add some preset viewports that can be switched via number keys (1, 2, 3 etc)
-
 * patch the entire expanded-ram imul8xe on top of imul8 to avoid the 3-cycle thunk penalty :D
 
 * optimize out a store/load with mul8_add16 and mul8_add24