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