From f647c68edf7a2b93b0cae1e2a62eaf69f9add80d Mon Sep 17 00:00:00 2001
From: hugova <hugova@kth.se>
Date: Fri, 1 Aug 2025 00:17:12 +0200
Subject: [PATCH] fix testing for divition and add doc.. for mult..

---
 host/src/routines/arithmatic/div_test.s      | 39 +++++++++++++++++---
 host/src/routines/arithmatic/div_test_zero.s | 18 +++++++++
 host/src/routines/arithmatic/mult_test.s     | 10 +++--
 3 files changed, 58 insertions(+), 9 deletions(-)
 create mode 100644 host/src/routines/arithmatic/div_test_zero.s

diff --git a/host/src/routines/arithmatic/div_test.s b/host/src/routines/arithmatic/div_test.s
index 8787132..2cd0a32 100644
--- a/host/src/routines/arithmatic/div_test.s
+++ b/host/src/routines/arithmatic/div_test.s
@@ -1,10 +1,37 @@
 ;;; -*- Mode: asm; indent-tabs-mode: t; tab-width: 8 -*-
-;;Calculates $EE /$05 = $33
+
+;; Note that the compile dont understand if its out of mem.
+;; Please run without linking other stuff. thats also why some code is commented out.
+;; Add it back in for debugging!
 .scope div_test
+        A_temp = $4043
         .include "arithmatic.inc"
-        LDA #$05
-        STA VAL_A
-        LDA #$02
-        STA VAL_B
-        JSR div; X = $02 if it works as it should
+        .repeat $16, i
+        .repeat $16, j
+        ;INC $400D ;; print number of iterations on screen.
+        LDX #i
+        STX VAL_A
+        STX A_temp
+        LDY #(j+1)
+        STY VAL_B
+        JSR div ; A = VAL_A / VAL_B, clobers X.
+        CPX #i/(j+1)
+        BEQ :+
+        jmp error
+        :
+        .endrepeat
+        .endrepeat
+        TXA
+        jmp end
+error:
+        TXA
+        ;; Error make screen read
+        ;; X * Y has the result in A that is wrong.
+        LDX #$02
+        STX $D020
+end:
+        LDX A_temp
+        ; X = VAL_A
+        ; Y = VAL_B
+        ; A = awnser.
 .endscope
diff --git a/host/src/routines/arithmatic/div_test_zero.s b/host/src/routines/arithmatic/div_test_zero.s
new file mode 100644
index 0000000..6e2509a
--- /dev/null
+++ b/host/src/routines/arithmatic/div_test_zero.s
@@ -0,0 +1,18 @@
+;;; -*- Mode: asm; indent-tabs-mode: t; tab-width: 8 -*-
+
+;; Test if division with 0 is not stuck in infinate loop.
+.scope div_test_zero
+        .include "arithmatic.inc"
+        .repeat $FF, i
+        INC $400D ;; print number of iterations on screen.
+        LDX #i
+        STX VAL_A
+        LDA #$00
+        STA VAL_B
+        JSR div ; A = VAL_A / VAL_B, clobers X.
+        .endrepeat
+paint:
+        ;; Donw make screen green
+        LDA #$13
+        STA $D020
+.endscope
diff --git a/host/src/routines/arithmatic/mult_test.s b/host/src/routines/arithmatic/mult_test.s
index 252a9a7..8c4d682 100644
--- a/host/src/routines/arithmatic/mult_test.s
+++ b/host/src/routines/arithmatic/mult_test.s
@@ -1,11 +1,12 @@
 ;;; -*- Mode: asm; indent-tabs-mode: t; tab-width: 8 -*-
-;;Calculates $11 * $0E = $EE
+
+;; Note that the compile dont understand if its out of mem.
+;; Please run without linking other stuff. thats also why some code is commented out.
 .scope mult_test
         A_temp = $4043
         B_temp = $4046
         .include "arithmatic.inc"
-        .repeat $0F, i ;; $15 = floor(sqrt($255))
-        ;; now i * j_max = $FF --> j_max = $FF/i
+        .repeat $0F, i
         .repeat $0F, j
         INC $400D ;; print number of iterations on screen.
         LDX #i
@@ -31,4 +32,7 @@ error:
 end:
         LDX A_temp
         LDY B_temp
+        ; X = VAL_A
+        ; Y = VAL_B
+        ; A = awnser.
 .endscope