Initial revision0_29alpha2

1 files changed, 149 insertions, 0 deletions

diff --git a/math.c b/math.c
new file mode 100644
index 000000000..5c1560a4e
--- /dev/null
+++ b/math.c
@@ -0,0 +1,149 @@
+#include "internal.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <math.h>
+
+/* Tiny RPN calculator, because "expr" didn't give me bitwise operations. */
+
+const char                      math_usage[] = "math expression ...";
+
+static double           stack[100];
+static unsigned int     pointer;
+
+static void
+push(double a)
+{
+        if ( pointer >= (sizeof(stack) / sizeof(*stack)) ) {
+                fprintf(stderr, "math: stack overflow\n");
+                exit(-1);
+        }
+        else
+                stack[pointer++] = a;
+}
+
+static double
+pop()
+{
+        if ( pointer == 0 ) {
+                fprintf(stderr, "math: stack underflow\n");
+                exit(-1);
+        }
+        return stack[--pointer];
+}
+
+static void
+add()
+{
+        push(pop() + pop());
+}
+
+static void
+sub()
+{
+        double  subtrahend = pop();
+
+        push(pop() - subtrahend);
+}
+
+static void
+mul()
+{
+        push(pop() * pop());
+}
+
+static void
+divide()
+{
+        double  divisor = pop();
+        push(pop() / divisor);
+}
+
+static void
+and()
+{
+        push((unsigned int)pop() & (unsigned int)pop());
+}
+
+static void
+or()
+{
+        push((unsigned int)pop() | (unsigned int)pop());
+}
+
+static void
+eor()
+{
+        push((unsigned int)pop() ^ (unsigned int)pop());
+}
+
+static void
+not()
+{
+        push(~(unsigned int)pop());
+}
+
+static void
+print()
+{
+        printf("%g\n", pop());
+}
+
+struct op {
+        const char *    name;
+        void                    (*function)();
+};
+
+static const struct op  operators[] = {
+        {       "add",  add     },
+        {       "and",  and     },
+        {       "div",  divide  },
+        {       "eor",  eor     },
+        {       "mul",  mul     },
+        {       "not",  not     },
+        {       "or",   or      },
+        {       "sub",  sub     },
+        {       0,              0       }
+};
+
+static void
+stack_machine(const char * argument)
+{
+        char *                          endPointer = 0;
+        double                          d;
+        const struct op *       o = operators;
+
+        if ( argument == 0 ) {
+                print();
+                return;
+        }
+
+        d = strtod(argument, &endPointer);
+
+        if ( endPointer != argument ) {
+                push(d);
+                return;
+        }
+
+        while ( o->name != 0 ) {
+                if ( strcmp(o->name, argument) == 0 ) {
+                        (*(o->function))();
+                        return;
+                }
+                o++;
+        }
+        fprintf(stderr, "math: %s: syntax error.\n", argument);
+        exit(-1);
+}
+
+int
+math_main(struct FileInfo * i, int argc, char * * argv)
+{
+        while ( argc >= 2 ) {
+                stack_machine(argv[1]);
+                argv++;
+                argc--;
+        }
+        stack_machine(0);
+        return 0;
+}