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 (ch == ' ' || ch == '\n');
  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         }
  80         else
  81                 f = number ();
  82
  83         return f;
  84 }
  85
  86 static long term (void)
  87 {
  88         long t = factor();
  89
  90         for (;;)
  91                 switch (ch) {
  92                 case '*':
  93                         next();
  94                         t *= factor();
  95                         break;
  96                 case '/':
  97                         next();
  98                         t /= factor();
  99                         break;
 100                 case '%':
 101                         next();
 102                         t %= factor();
 103                         break;
 104                 default:
 105                         return t;
 106                 }
 107 }
 108
 109
 110 static long expr(void)
 111 {
 112         long e;
 113
 114         if (ch == '+') {
 115                 next();
 116                 e = term ();
 117         } else if (ch == '-') {
 118                 next();
 119                 e = - term ();
 120         } else
 121                 e = term ();
 122
 123         while (ch == '+' || ch == '-') {
 124                 char op = ch;
 125                 next();
 126                 if (op == '-')
 127                         e -= term ();
 128                 else
 129                         e += term ();
 130         }
 131         return e;
 132 }
 133
 134 long eval_arg(char *arg, char **end_ptr)
 135 {
 136         long val;
 137
 138         start_p = arg;
 139         bp = arg;
 140         next();
 141         if (setjmp (eval_jbuf) != 0) {
 142                 if (!end_ptr) {
 143                         print_error_pos();
 144                         longjmp(cmd_jbuf, 1);
 145                 }
 146                 val = -1;
 147         } else {
 148                 val = expr ();
 149                 --bp;
 150         }
 151
 152         if (!end_ptr) {
 153                 if (*bp != '\0') {
 154                         print_error_pos();
 155                         longjmp(cmd_jbuf, 1);
 156                 }
 157         } else
 158                 *end_ptr = bp;
 159
 160         return val;
 161 }