From 7136a8d938c38535d13a8ff5b5aee3ad2c8be512 Mon Sep 17 00:00:00 2001
From: Syndamia <kamen@syndamia.com>
Date: Fri, 1 Aug 2025 13:06:38 +0300
Subject: fix(isprime): Fix off by one value of y in loop

---
 isprime/isprime.oph.s | 49 +++++++++++++++++++++++++++++++++----------------
 isprime/kernal.oph.s  |  3 +++
 2 files changed, 36 insertions(+), 16 deletions(-)

diff --git a/isprime/isprime.oph.s b/isprime/isprime.oph.s
index 30730de..618bd6d 100644
--- a/isprime/isprime.oph.s
+++ b/isprime/isprime.oph.s
@@ -6,22 +6,40 @@
 .require "basic_starter.oph.s"
 .require "kernal.oph.s"
 
-.alias check_first 13
-.alias check_last  40
+.alias check_first 0
+.alias check_last  254
 
 main:
-.scope
          `lowercase
+         ;`primes_yn check_first, check_last
+         `primes_list check_first, check_last
+         rts
 
-         ldx #check_first ; x = check_first
-*        jsr isprimex_yn  ; do  print isprime(x)
-         inx              ;     ++x
-         cpx #check_last  ; while (x <= check_last)
-         bcc -
-         beq -
+.macro primes_list
+         ldx #_1         ; x = check_first
+_loop:   jsr isprimex_print ; do  print isprime(x)
+         inx             ;     ++x
+         cpx #_2         ; while (x <= check_last)
+         bcc _loop
+         beq _loop
+.macend
+
+.macro primes_yn
+         ldx #_1         ; x = check_first
+_loop:   jsr isprimex_yn ; do  print isprime(x)
+         inx             ;     ++x
+         cpx #_2         ; while (x <= check_last)
+         bcc _loop
+         beq _loop
+.macend
 
-_end:    rts
-.scend
+; prints x if it is a prime
+isprimex_print:
+         jsr isprimex  ; a = isprime(x)
+         beq +         ; if (a != 0)
+         jsr printx    ;   print x
+         `printchar 32 ;   print " "
+*        rts           ; return
 
 ; prints "$x Yes\n" when x is prime and "$x No\n" otherwise
 isprimex_yn:
@@ -59,10 +77,10 @@ isprimex:
          stx max    ; max = x
          lsr max    ; max /= 2
 
-_loop:   cpy max    ; do  if (y >= max)
-         bcs _true  ;       return True
+         cpy max    ; if (y >= max)
+         bcs _true  ;   return True
 
-         dey        ;     --y
+_loop:   dey        ; do  --y
          txa        ;     a = x
          `mody      ;     if (a % y == 0)
          beq _end   ;       return False
@@ -78,8 +96,7 @@ _loop:   cpy max    ; do  if (y >= max)
          iny        ;     ++y
          iny        ;     ++y
          iny        ;     ++y
-         iny        ;     ++y
-         cpy #5     ; while (y < max)
+         cpy max    ; while (y < max)
          bcc _loop
 
 _true:   lda #1     ; return True
diff --git a/isprime/kernal.oph.s b/isprime/kernal.oph.s
index 2082d6b..239df49 100644
--- a/isprime/kernal.oph.s
+++ b/isprime/kernal.oph.s
@@ -25,6 +25,9 @@
          jsr printa
 .macend
 
+printy:  tya         ; a = y
+         jmp printa
+
 ; print register x as a number
 printx:  txa         ; a = x
 
-- 
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