feat(isprime): Print numbers and their prime results for a (dynamic) range of values

2 files changed, 126 insertions, 35 deletions

diff --git a/isprime/isprime.oph.s b/isprime/isprime.oph.s
index e4824fa..e58852b 100644
--- a/isprime/isprime.oph.s
+++ b/isprime/isprime.oph.s
@@ -6,50 +6,64 @@
 .require "basic_starter.oph.s"
 .require "kernal.oph.s"
 
-number:  .word 15
+.alias check_first 97
+.alias check_last  104
 
 main:
+.scope
          `lowercase
-         jsr isprime ; a = isprime(number)
-         bne +       ; if (a == 0)
-         `print no   ;   print "No"
-         rts         ;   return
-*        `print yes  ; else print "Yes"
-         rts         ;   return
 
-isprime:
-.scope
-         lda #1         ; if (number & 0b0001 == 0)
-         and number
-         beq _end       ;   return False
-         ;`mod number, 3 ; if (number % 3 == 0)
-         ;beq _end       ;   return False
-         lda number
-         ldx #3
-         stx mod_n
-         jsr mod_addr
+         ldx #check_first ; x = check_first
+*        jsr printx       ; do  print x
+         lda #32          ;     print " "
+         jsr putchar
+         jsr isprimex_cli ;     print isprime(x)
+         lda #13          ;     print "\n"
+         jsr putchar
+
+         inx              ;     ++x
+         txa              ; while (x <= check_last)
+         cmp #check_last
+         bcc -
+         beq -
+
 _end:    rts
 .scend
 
-.macro mod ; 12 cycles (2+4+2+2+2) raw
-         sec       ; carry = 0
-         lda _1    ; a = _1
-_loop:   sbc #_2   ; do  a -= _2 + carry
-         beq _end  ;     if (a == 0) break
-         bpl _loop ; while (a >= 0)
-_end:
-.macend
-
-mod_n:   .word 0
+isprimex_cli:
+         jsr isprimex ; a = isprime(number)
+         beq +        ; if (a != 0)
+         `print yes   ;   print "Yes"
+         rts          ;   return
+*        `print no    ; else print "No"
+         rts          ;   return
 
-; a % mod_n
-mod_addr: ; 16 cycles (2+4+2+2+6) raw + 18 cycles (4+4+4+6) raw for arguments
+isprimex:
 .scope
-         sec       ; carry = 0
-_loop:   sbc mod_n ; do  a -= mod_n + carry
-         beq _end  ;     if (a == 0) break
-         bpl _loop ; while (a >= 0)
+         sec            ; if (number < 2) // equivalent to "number <= 1"
+         txa            ;   // a = x
+         sbc #2         ;   // a -= 2 + 0
+         bmi _negative  ;   return False
+
+         sbc #2         ; if (number < 2) // since it was already subtracted, this is equal to "number < 4" or "number <= 3"
+         bmi _end       ;   return True
+
+         txa            ; if (number % 2 == 0)
+         and #1         ;   // number & 0b0001 == 0
+         beq _end       ;   return False
+
+         txa
+         `mod 3        ; if (number % 3 == 0)
+         beq _end       ;   return False
+
+         ;lda number
+         ;ldx #3
+         ;stx mod_n
+         ;jsr mod_addr
 _end:    rts
+
+_negative: lda #0
+           rts
 .scend
 
 .charmap 'A, "abcdefghijklmnopqrstuvwxyz"
diff --git a/isprime/kernal.oph.s b/isprime/kernal.oph.s
index a9fd007..b39d212 100644
--- a/isprime/kernal.oph.s
+++ b/isprime/kernal.oph.s
@@ -2,13 +2,90 @@
 
 ; print [null-terminated string start address]
 .macro print
+         txa          ; backup = x
+         pha
          ldx #0       ; x = 0
  _loop:  lda _1, x    ; while (_1[x] != 0) {
          beq _done
          jsr putchar  ;    putchar(_1[x])
          inx          ;    ++x
          bne _loop    ;    if (x == 0) break }  This allows max 255 character to be read
- _done:
+ _done:  pla          ; x = backup
+         tax
+.macend
+
+printx:
+.scope
+         txa         ; a = x
+         cmp #10     ; if (a < 10)
+         bcc _1digit
+         cmp #100    ; if (a < 100)
+         bcc _2digit
+
+_3digit: pha
+         `div 100
+         clc
+         adc #'0
+         jsr putchar
+         pla
+         `mod 100
+
+_2digit: pha
+         `div 10
+         clc
+         adc #'0
+         jsr putchar
+         pla
+         `mod 10
+
+_1digit: clc
+         adc #'0
+         jsr putchar
+         rts
+.scend
+
+; a = a % _1
+.macro mod         ; 10 cycles (2+2+2+2+2) raw
+         cmp #_1   ; if (a < _1) return
+         bcc _end
+
+         sec       ; carry = 1
+_loop:   sbc #_1   ; do  a -= _1 + !carry
+         beq _end  ;     if (a == 0) break
+         cmp #_1   ; while (a >= _1)
+         bcs _loop
+_end:
+.macend
+
+buffer: .byte 0
+
+; a = a / _1
+.macro div
+         ora #0      ; The CMP (and friends) instruction changes the carry and zero flag,
+                     ; which can cause the flags (and therefore the branch instructions)
+                     ; to get "desynced" with the actual accumulator value.
+                     ; With this instruction, we force a "refresh" of the flags.
+                     ; It took me half an hour to figure this out...
+
+         beq _return ; if (a == 0) return 0
+         cmp #_1     ; if (a < _1) return 0
+         bcc _zero
+
+         stx buffer ; buffer = x
+         ldx #0     ; x = 0
+         sec        ; carry = 1
+_loop:   sbc #_1    ;   a -= _1 + !carry
+         inx        ;   ++x
+         beq _end   ;   if (a == 0) break
+         cmp #_1    ; while (a >= _1)
+         bcs _loop
+
+_end:    txa         ; a = x
+         ldx buffer  ; x = buffer
+         jmp _return
+
+_zero:   lda #0
+_return:
 .macend
 
 .macro lowercase