From d4024687958fbaa993e7637d8cfc55ac0706a1bc Mon Sep 17 00:00:00 2001
From: rzuckerm <rzdulc@gmail.com>
Date: Mon, 16 Mar 2026 19:20:30 -0500
Subject: [PATCH 1/3] Add Prime Number in ALGOL 60

---
 archive/a/algol60/prime-number.alg | 127 +++++++++++++++++++++++++++++
 1 file changed, 127 insertions(+)
 create mode 100644 archive/a/algol60/prime-number.alg

diff --git a/archive/a/algol60/prime-number.alg b/archive/a/algol60/prime-number.alg
new file mode 100644
index 000000000..3c335cfa1
--- /dev/null
+++ b/archive/a/algol60/prime-number.alg
@@ -0,0 +1,127 @@
+begin
+    procedure usage;
+    begin
+        outstring(1, "Usage: please input a non-negative integer\n");
+        stop
+    end usage;
+
+    comment Input a digit character from stdin and return the following:
+        - "0" to "9" maps to 0 to 9
+        - "+" maps to 10
+        - "-" maps to 11
+        - whitespace maps to 12
+        - comma maps to 13
+        - null byte maps to -1
+        - invalid bytes map to -2;
+    integer procedure indigit;
+    begin
+        comment Mapping:
+            - "0" to "9" maps to 1 to 10
+            - "+" maps to 11
+            - "-" maps to 12
+            - "," mapps to 13
+            - "\t" maps to 14
+            - "\r" maps to 15
+            - "\n" maps to 16
+            - " " maps to 17
+            - null byte maps to 18
+            - invalid byte maps 0;
+        integer ch;
+        inchar(0, "0123456789+-,\t\r\n ", ch);
+        if ch < 1 then ch := -2
+        else if ch < 14 then ch := ch - 1
+        else if ch < 18 then ch := 12
+        else ch := -1;
+        indigit := ch
+    end indigit;
+
+    comment Input an integer from stdin into 'result' and parse it.
+        The last character is read into 'ch'.
+        return true if integer is valid, false otherwise;
+    boolean procedure inValidInteger(result, ch);
+    integer result, ch;
+    begin
+        boolean valid;
+        integer s;
+
+        result := 0;
+        valid := false;
+        s := 1;
+
+        comment Ignore whitespace;
+        for ch := indigit while ch = 12 do indigit;
+
+        comment Process signs: ignore "+" and invert sign if "-";
+    signloop:
+        if ch = 10 | ch = 11 then
+        begin
+            if ch = 11 then s := -s;
+            ch := indigit;
+            goto signloop
+        end;
+
+        comment Process digits: update value;
+    valueloop:
+        if ch >= 0 & ch <= 9 then
+        begin
+            comment Invalid if overflow or underflow;
+            valid := false;
+            if (s > 0 & (maxint - ch) % 10 < result) |
+                (s < 0 & (-1 - maxint + ch) % 10 > result) then goto done;
+
+            result := result * 10 + s * ch;
+            ch := indigit;
+            valid := true;
+            goto valueloop
+        end;
+
+        comment Ignore whitespace;
+        for ch := ch while ch = 12 do ch := indigit;
+
+    done:
+        inValidInteger := valid
+    end inValidInteger;
+
+    integer procedure mod(x, n);
+    value x, n;
+    integer x, n;
+    begin
+        mod := x - n * (x % n)
+    end mod;
+
+    boolean procedure isprime(x);
+    value x;
+    integer x;
+    begin
+        boolean result;
+        integer i, q;
+
+        result := x = 2 | (x > 2 & mod(x, 2) != 0);
+        i := 3;
+        q := entier(sqrt(x));
+
+    primeloop:
+        if result & i <= q then
+        begin
+            result := mod(x, i) != 0;
+            i := i + 2;
+            goto primeloop
+        end;
+
+        isprime := result
+    end isprime;
+
+    integer argc, result, ch;
+
+    comment Get number of parameters. Exit if too few;
+    ininteger(0, argc);
+    if argc < 1 then usage;
+
+    comment Get integer value from 1st argument. Exit if invalid, not
+        end of argument, or negative;
+    if !inValidInteger(result, ch) | ch != -1 | result < 0 then usage;
+
+    comment Output "prime" if number is prime, "composite" otherwise;
+    if isprime(result) then outstring(1, "prime")
+    else outstring(1, "composite")
+end

From f2a00ba939ac627e295ae9f194d410e12315fb70 Mon Sep 17 00:00:00 2001
From: rzuckerm <rzdulc@gmail.com>
Date: Mon, 16 Mar 2026 19:41:45 -0500
Subject: [PATCH 2/3] Use for loop

---
 archive/a/algol60/prime-number.alg | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/archive/a/algol60/prime-number.alg b/archive/a/algol60/prime-number.alg
index 3c335cfa1..e176e15a8 100644
--- a/archive/a/algol60/prime-number.alg
+++ b/archive/a/algol60/prime-number.alg
@@ -97,17 +97,14 @@ begin
         integer i, q;
 
         result := x = 2 | (x > 2 & mod(x, 2) != 0);
-        i := 3;
         q := entier(sqrt(x));
-
-    primeloop:
-        if result & i <= q then
+        for i := 3 step 2 until q do
         begin
             result := mod(x, i) != 0;
-            i := i + 2;
-            goto primeloop
+            if !result then goto done
         end;
 
+    done:
         isprime := result
     end isprime;
 

From f6ef8e97a185e6e3432b846a83f833104e791952 Mon Sep 17 00:00:00 2001
From: rzuckerm <rzdulc@gmail.com>
Date: Mon, 16 Mar 2026 19:44:12 -0500
Subject: [PATCH 3/3] Add if around for loop

---
 archive/a/algol60/prime-number.alg | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/archive/a/algol60/prime-number.alg b/archive/a/algol60/prime-number.alg
index e176e15a8..62207b504 100644
--- a/archive/a/algol60/prime-number.alg
+++ b/archive/a/algol60/prime-number.alg
@@ -97,11 +97,14 @@ begin
         integer i, q;
 
         result := x = 2 | (x > 2 & mod(x, 2) != 0);
-        q := entier(sqrt(x));
-        for i := 3 step 2 until q do
+        if result then
         begin
-            result := mod(x, i) != 0;
-            if !result then goto done
+            q := entier(sqrt(x));
+            for i := 3 step 2 until q do
+            begin
+                result := mod(x, i) != 0;
+                if !result then goto done
+            end
         end;
 
     done: