From 3fa7d73e70651dc90305f4f16a189bdd257b1c9d Mon Sep 17 00:00:00 2001
From: not_a_robot06 <temporarythrowaway@tutamail.com>
Date: Sun, 16 Feb 2025 10:33:39 +0000
Subject: handle up/down cursor movement

- use GETIN kernal routine for handling input than my old crappy way
- CLRCHN clears keyboard buffer before use
- reset now clears screen
- add subroutines a16b and s16b to add and subtract to num, respectively
---
 life.asm | 73 ++++++++++++++++++++++++++++++++++++----------------------------
 1 file changed, 41 insertions(+), 32 deletions(-)

(limited to 'life.asm')

diff --git a/life.asm b/life.asm
index 2745dc6..44e3996 100644
--- a/life.asm
+++ b/life.asm
@@ -5,7 +5,9 @@ numL := $02 ; low byte of a 16-bit number
 numH := $03 ; low byte of a 16-bit number
 key_buf_len := $c6
 key_buf := $0277
+GETIN := $ffe4
 CHROUT := $ffd2
+CLRCHN := $e544
 
 ; initialisation: clear screen and set num to point to screen mem start
 init:
@@ -18,17 +20,22 @@ init:
   sta numH
   lda #$00
   sta numL
+  jsr CLRCHN
   jmp loop
 
 ; main loop
 loop:
-  jsr key_wait
-  lda key_buf
+  jsr GETIN
+  beq loop
 
   cmp #$1d ; right arrow
   beq if_right
   cmp #$9d ; left arrow
   beq if_left
+  cmp #$91 ; up arrow
+  beq if_up
+  cmp #$11 ; down arrow
+  beq if_down
   cmp #$2d ; reset if - pressed
   beq if_reset
   cmp #$20 ; fill cell if space pressed
@@ -45,11 +52,19 @@ if_left:
   jsr dec_num
   jmp loop
 
+if_up:
+  lda #40
+  jsr s16b
+  jmp loop
+
+if_down:
+  lda #40
+  jsr a16b
+  jmp loop
+
 if_reset:
-  lda #$04
-  sta numH
-  lda #$00
-  sta numL
+  lda #$93
+  jsr CHROUT
   jmp loop
 
 if_space:
@@ -67,20 +82,6 @@ if_cell_empty:
   jsr print_byte
   jmp loop
 
-
-; loops until keyboard buffer has any number of characters in it
-key_wait:
-  pha
-key_wait_loop:
-  lda key_buf_len ; shows how many keys are in key buffer
-  cmp #$00
-  beq key_wait_loop
-
-  lda #$00
-  sta key_buf_len
-  pla
-  rts
-
 ; print byte in A at location in num
 print_byte:
   ; init: store original A in X and push Y to stack
@@ -98,22 +99,30 @@ print_byte:
   txa
   rts
 
-; adds A to num (16 bit) (NOT WORKING)
-; destroys: X
+; adds A to num
 a16b:
+  clc
+  adc numL
+  sta numL
+  lda #$00
+  adc numH
+  sta numH
+  rts
+
+; subtracts A from num
+s16b:
   pha
-  tsx
   lda numL
-  adc $0100,x
+  tsx
+  inx
+  sec
+  sbc $0100,x
   sta numL
-  bcs a16b_carry
-  jmp a16b_end
-  a16b_carry:
-    inc numH
-  a16b_end:
-    clc
-    pla
-    rts
+  lda numH
+  sbc #$00
+  sta numH
+  pla
+  rts
 
 inc_num:
   inc numL
-- 
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