feat: add msiArithPostprocess function to msi

* add msiArithTest.template

Author: jerzyjamroz

modules/database/src/ioc/dbtemplate/Makefile

@@ -4,7 +4,7 @@
 # Copyright (c) 2002 The Regents of the University of California, as
 #     Operator of Los Alamos National Laboratory.
 # EPICS BASE is distributed subject to a Software License Agreement found
-# in file LICENSE that is included with this distribution. 
+# in file LICENSE that is included with this distribution.
 #*************************************************************************
 
 # This is a Makefile fragment, see src/ioc/Makefile.
@@ -13,15 +13,15 @@ SRC_DIRS += $(IOCDIR)/dbtemplate
 
 PROD_HOST += msi
 
-msi_SRCS = msi.cpp
+msi_SRCS = msi.cpp msiArith.cpp
 msi_SYS_LIBS_WIN32 = shlwapi
 DOCS += msi.md
 
 INC += dbLoadTemplate.h
 INC += dbtoolsIocRegister.h
+INC += msiArith.h
 
 dbCore_SRCS += dbLoadTemplate.c
 dbCore_SRCS += dbtoolsIocRegister.c
 
 CLEANS += dbLoadTemplate_lex.c dbLoadTemplate.c
-

modules/database/src/ioc/dbtemplate/msi.cpp

@@ -13,6 +13,8 @@
 #include <string>
 #include <list>
 
+#include "msiArith.h"
+
 #include <stdlib.h>
 #include <stddef.h>
 #include <stdio.h>
@@ -361,6 +363,7 @@ static void makeSubstitutions(inputData * const inputPvt,
         if (expand && !opt_D) {
             STEP("Expanding to output stream");
             n = macExpandString(macPvt, input, buffer, MAX_BUFFER_SIZE - 1);
+            msiArithPostprocess(buffer); //add expression evaluation
             fputs(buffer, stdout);
             if (opt_V == 1 && n < 0) {
                 fprintf(stderr, "msi: Error - undefined macros present\n");

modules/database/src/ioc/dbtemplate/msiArith.cpp

@@ -0,0 +1,61 @@
+#include <cstdlib>
+#include <cstdio>
+#include <cstring>
+
+// Detect digit
+static inline bool isDigit(char c) { return c >= '0' && c <= '9'; }
+
+// Detect digit or "-digit"
+static inline bool isInteger(const char* p)
+{
+    return isDigit(*p) || (*p == '-' && p[1] && isDigit(p[1]));
+}
+
+void msiArithPostprocess(char* buffer)
+{
+    if (!buffer) return;
+
+    size_t r = 0, w = 0;
+
+    while (buffer[r]) {
+
+        if (isInteger(buffer + r)) {
+
+            char* end1 = nullptr;
+            long long base = std::strtoll(buffer + r, &end1, 0);
+            size_t j = (size_t)(end1 - buffer);
+
+            if (buffer[j] == '~' &&
+                buffer[j + 1] == '(' &&
+                (buffer[j + 2] == '+' || buffer[j + 2] == '-'))
+            {
+                char sign = buffer[j + 2];
+
+                char* end2 = nullptr;
+                long long off = std::strtoll(buffer + j + 3, &end2, 0);
+
+                if (end2 != (buffer + j + 3) && *end2 == ')') {
+                    long long res = (sign == '+') ? (base + off) : (base - off);
+
+                    char tmp[64];
+                    int m = std::snprintf(tmp, sizeof(tmp), "%lld", res);
+                    if (m > 0) {
+                        std::memcpy(buffer + w, tmp, (size_t)m);
+                        w += (size_t)m;
+                    }
+
+                    r = (size_t)((end2 - buffer) + 1); // skip ')'
+                    continue;
+                }
+            }
+
+            // no match -> copy original number text
+            while (r < j) buffer[w++] = buffer[r++];
+            continue;
+        }
+
+        buffer[w++] = buffer[r++];
+    }
+
+    buffer[w] = '\0';
+}

modules/database/src/ioc/dbtemplate/msiArith.h

@@ -0,0 +1,9 @@
+#ifndef MSI_ARITH_H
+#define MSI_ARITH_H
+
+#include <string>
+
+// In-place: <number>~(+<number>) or <number>~(-<number>), no spaces.
+void msiArithPostprocess(char* buffer);
+
+#endif

modules/database/test/ioc/db/msiArithTest.template

@@ -0,0 +1,24 @@
+# Minimal test for post-arithmetic: <number>~(+N) / <number>~(-N)
+# Run example:
+#   msi -M"P=ArithTest,TESTNUM=99" msiArithTest.template
+
+record(stringin, "$(P):orig") {
+    field(VAL,  "$(TESTNUM)")
+    field(DESC, "orig: $(TESTNUM)")
+}
+
+record(stringin, "$(P):plus1") {
+    field(VAL,  "$(TESTNUM)~(+1)")
+    field(DESC, "plus1: $(TESTNUM)~(+1)")
+}
+
+record(stringin, "$(P):minus1") {
+    field(VAL,  "$(TESTNUM)~(-1)")
+    field(DESC, "minus1: $(TESTNUM)~(-1)")
+}
+
+# Should NOT change
+record(stringin, "$(P):spaces_should_stay") {
+    field(VAL,  "$(TESTNUM) ~ (+1)")
+    field(DESC, "spaces: $(TESTNUM) ~ (+1)")
+}