avr/eval_arg.c

   1 /*
   2  * (C) Copyright 2016 Leo C. <erbl259-lmu@yahoo.de>
   3  *
   4  * SPDX-License-Identifier:     GPL-2.0
   5  */
   6
   7 #include "eval_arg.h"
   8 #include "common.h"
   9 #include <stdlib.h>
  10 #include <ctype.h>
  11 #include <setjmp.h>
  12 #include "print-utils.h"
  13 #include "command.h"    /* jump_buf */
  14
  15 static jmp_buf eval_jbuf;
  16 static char ch;
  17 static char *start_p;
  18 static char *bp;
  19
  20
  21 static long expr(void);
  22
  23 static void print_error_pos(void)
  24 {
  25         printf_P(PSTR("Arg: '%s'\n"
  26                       "      "), start_p);
  27         print_blanks(bp - start_p);
  28         my_puts_P(PSTR("^syntax error!\n"));
  29 }
  30
  31 static void error (void)
  32 {
  33         --bp;
  34         longjmp (eval_jbuf, 1);
  35 }
  36
  37 static void next(void)
  38 {
  39         do
  40                 ch = *bp++;
  41         while (isspace(ch));
  42 }
  43
  44 static long number (void)
  45 {
  46         int base = 16;
  47         char *end_p;
  48         long n;
  49
  50         if (ch == '$') {                                        /* FIXME: should be '#' */
  51                 next();
  52                 base = 10;
  53         }
  54         if (!isdigit(ch) && !(base == 16 && isxdigit(ch)))
  55                 error ();
  56
  57         n = strtoul(bp - 1, &end_p, base);
  58
  59         if (end_p == bp - 1)
  60                 error();
  61         bp = end_p;
  62         next();
  63
  64         return n;
  65 }
  66
  67 static long factor (void)
  68 {
  69         long f;
  70
  71         if (ch == '(')
  72         {
  73                 next();
  74                 f = expr();
  75                 if (ch == ')')
  76                         next();
  77                 else
  78                         error ();
  79         } else {
  80                 char sign = ch;
  81                 if (sign == '+' || sign == '-') {
  82                         next();
  83                 }
  84                 f = number();
  85                 if (sign == '-')
  86                         f = -f;
  87         }
  88         return f;
  89 }
  90
  91 static long term (void)
  92 {
  93         long t = factor();
  94
  95         for (;;)
  96                 switch (ch) {
  97                 case '*':
  98                         next();
  99                         t *= factor();
 100                         break;
 101                 case '/':
 102                         next();
 103                         t /= factor();
 104                         break;
 105                 case '%':
 106                         next();
 107                         t %= factor();
 108                         break;
 109                 default:
 110                         return t;
 111                 }
 112 }
 113
 114
 115 static long expr(void)
 116 {
 117         long e = term ();
 118
 119         while (ch == '+' || ch == '-') {
 120                 char op = ch;
 121                 next();
 122                 if (op == '-')
 123                         e -= term ();
 124                 else
 125                         e += term ();
 126         }
 127         return e;
 128 }
 129
 130 long eval_arg(char *arg, char **end_ptr)
 131 {
 132         long val;
 133
 134         start_p = arg;
 135         bp = arg;
 136         next();
 137         if (setjmp (eval_jbuf) != 0) {
 138                 if (!end_ptr) {
 139                         print_error_pos();
 140                         longjmp(cmd_jbuf, 1);
 141                 }
 142                 val = -1;
 143         } else {
 144                 val = expr ();
 145                 --bp;
 146         }
 147
 148         if (!end_ptr) {
 149                 if (*bp != '\0') {
 150                         print_error_pos();
 151                         longjmp(cmd_jbuf, 1);
 152                 }
 153         } else
 154                 *end_ptr = bp;
 155
 156         return val;
 157 }