/*
 * (C) Copyright 2003
 * Tait Electronics Limited, Christchurch, New Zealand
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */


/*
 * This file provides an 'eval' function. It is very crude and can only set a variable, not pass
 * the result directly back to an inline calculation.
 * It supports binary operators +, -, *, /, &, |
 */
 


#include <common.h>
#include <config.h>
#include <command.h>

#if (CONFIG_COMMANDS & CFG_CMD_EVAL)

#define PLUS	0
#define MINUS	1
#define TIMES	2
#define DIVIDE	3
#define LAND	4
#define LOR	5
#define LXOR	6


static struct op_tbl_s {
	char	*op;		/* operator string */
	int	opcode;		/* internal representation of opcode */
};

typedef struct op_tbl_s op_tbl_t;

static op_tbl_t op_table [] = {
	{"+", PLUS},
	{"-", MINUS},
	{"*", TIMES},
	{"/", DIVIDE},
	{"&", LAND},
	{"|", LOR},
	{"^", LXOR},
};
	
#define op_tbl_size (sizeof(op_table)/sizeof(op_table[0]))



extern int cmd_get_data_size(char* arg, int default_size);


static long evalexp(char *s, int w)
{
	long l, *p;
  
/* if the parameter starts with a * then assume is a pointer to the value we want */  
	if (s[0] == '*') {
		p = (long *)simple_strtoul(&s[1], NULL, 16);
		l = *p;
	} else {
		l = simple_strtoul(s, NULL, 16);
	}
  
	return (l & ((1 << (w * 8)) - 1));
}


static int arith (char *s, char *t, int op, int w)
{
	long l, r;

	l = evalexp (s, w);
	r = evalexp (t, w);

	switch (op) {
	case PLUS: return (l + r);
	case MINUS: return (l - r);
	case TIMES: return (l * r);
	case DIVIDE: return (l / r);
	case LAND: return (l & r);
	case LOR: return (l | r);
	case LXOR: return (l ^ r);
	}

	return (0);
}


/* command line interface to the shell test */
int do_eval ( cmd_tbl_t *cmdtp, int flag, int argc, char *argv[] )
{
	int 	w, len, i;
	op_tbl_t *optp;
	char	*op, buf[32];
	long value;


        /* Validate arguments */
        if ((argc != 5)){
		printf("Usage:\n%s\n", cmdtp->usage);
        	return 1;
        }
	
	/* Check for a data width specification.
	 * Defaults to long (4) if no specification.
	 * Uses -2 as 'width' for .s (string) so as not to upset existing code
	 */
	switch (w = cmd_get_data_size(argv[0], 4)) {
	case 1:
	case 2:
	case 4:
		op = argv[3];
		len = strlen(op);

		for (optp = (op_tbl_t *)&op_table, i = 0; i < op_tbl_size; optp++, i++) {

			if ((strncmp (op, optp->op, len) == 0) && (len == strlen (optp->op))) {
				value = arith(argv[2], argv[4], optp->opcode, w);
				sprintf(buf, "%lx", value);
				setenv(argv[1], buf);
				return 0;
			}
		}
		printf("Unknown operator '%s'\n", op);

		break;
	case -1:
		puts("Invalid data width specifier\n");
		break;
	}

	return 0;
}	

U_BOOT_CMD(
	eval, 5, 0, do_eval,
	"eval    - set var from arithmetic operation\n",
	"[.b, .w, .l] var [*]value1 <op> [*]value2\n"
);

#endif /* CONFIG_CMD_EVAL */



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