[LINT68][COMMITTED] Add operator L from LongInt to string

[Jose E. Marchesi]

The original code from Baszenski features read routines to be used
with the transput ("read" for Lints).  Since we don't have the general
transput yet, I have added a new operator L that, given a LongInt,
yields the textual representation.  It is the reverse of longwhole.
---
 src/liblint68.a68           | 36 ++++++++++++++++++++++++++++++++++--
 testsuite/Makefile.am       |  7 +++++--
 testsuite/test-l-string.a68 | 25 +++++++++++++++++++++++++
 3 files changed, 64 insertions(+), 4 deletions(-)
 create mode 100644 testsuite/test-l-string.a68

diff --git a/src/liblint68.a68 b/src/liblint68.a68
index dc3db8c..3b6bb2f 100644
--- a/src/liblint68.a68
+++ b/src/liblint68.a68
@@ -12,7 +12,9 @@
   1. Adapt from the point stropping used in the published work to
      modern stropping supported by ga68.
   2. Added some additional commentary.
-  3. Several code improvements.
+  3. The input routines has been replaced with an operator L
+     that gets a string.
+  4. Several other code improvements.
 
   Note that the origin form of this code is Copyright 1983
   Rechenzentrum der Ruhr-Universitaet, published in the form of a book
@@ -134,7 +136,9 @@ def
       Note that 0:-1 bounds are used instead of the customary 1:0 so
       that checking for non-zero can be done by UPB abs'u > 0 }
 
-    LongInt zero = (plus_sign, heap[0:-1]ShortInt);
+    LongInt zero; {XXX GCC bug = (plus_sign, heap[0:-1]ShortInt);}
+    sign'zero := plus_sign;
+    abs'zero := heap[0:-1]ShortInt;
 
     { The algorithms for arithmetic with LongInt values are
       essentially those described in D.E. Knuth: The Art of Computing
@@ -769,6 +773,34 @@ def
     { Input and conversion routines
       ───────────────────────────── }
 
+    pub op L = (string s) LongInt:
+    begin
+          LongInt result := zero;
+          bool gotsign := false, negative := false, strange := false;
+
+          for i to UPB s while ~strange
+          do if s[i] = "-"
+             then if gotsign
+                  then strange := true
+                  else negative := true;
+                       gotsign := true
+                  fi
+             elif s[i] = "+"
+             then if gotsign
+                  then strange := true
+                  else negative := false;
+                       gotsign := true
+                  fi
+             elif s[i] = blank
+             then skip
+             elif ABS s[i] >= ABS "0" AND ABS s[i] <= ABS "9"
+             then result *:= 10 +:= (ABS s[i] - ABS "0")
+             else strange := true
+             fi
+          od;
+          (negative | -result | result)
+    end;
+    
     pub proc longwhole = (LongInt x, int width) string:
     begin
           LongInt absx := ABS x;
diff --git a/testsuite/Makefile.am b/testsuite/Makefile.am
index edd6bbe..99150f3 100644
--- a/testsuite/Makefile.am
+++ b/testsuite/Makefile.am
@@ -18,12 +18,15 @@
 
 AM_A68FLAGS = -I$(top_builddir)/src/.libs -std=gnu68 -fcheck=nil
 
-TESTS = test-rel-ops test-fac
+TESTS = test-rel-ops test-fac test-l-string
 
-noinst_PROGRAMS = test-rel-ops test-fac
+noinst_PROGRAMS = test-rel-ops test-fac test-l-string
 
 test_rel_ops_SOURCES = test-rel-ops.a68
 test_rel_ops_LDADD = $(top_builddir)/src/liblint68.la
 
 test_fac_SOURCES = test-fac.a68
 test_fac_LDADD = $(top_builddir)/src/liblint68.la
+
+test_l_string_SOURCES = test-l-string.a68
+test_l_string_LDADD = $(top_builddir)/src/liblint68.la
diff --git a/testsuite/test-l-string.a68 b/testsuite/test-l-string.a68
new file mode 100644
index 0000000..5b5e2bc
--- /dev/null
+++ b/testsuite/test-l-string.a68
@@ -0,0 +1,25 @@
+{ test-l-string - Unit tests for liblint68 - from string to lint
+
+  Copyright (C) 2026 Jose E. Marchesi
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+}
+
+access Lint68
+begin
+      assert (L "2432902008176640000" = FAC 20);
+      assert (L "+2432902008176640000" = FAC 20);
+      assert (L "815915283247897734345611269596115894272000000000" = FAC 40)
+
+end
-- 
2.39.5