Hermit-at-1.1.3,一款bootloader

				/*				 * Copyright (c) 2000 Blue Mug, Inc.  All Rights Reserved.				 */								#include 				#include 				#include 				#include 								/* command line length limits */				#define MAXARGS 16				#define MAXLEN 256								/* character constants */				#define LF      '\n'				#define CR      '\r'				#define BS      0x08				#define DEL     0x7F				#define ISWSP(c) ((c)==' ' || (c)=='\t' || (c)=='\r' || (c)=='\n')								/* global data that's part of the API */				void (*errfunc)();				union errdata errdata;								/* static global data */				static command_list_t *top_command_list;				static int interactive = 1;								/* do_command scribbles on cmdline! */				static int do_command(const command_list_t *cmdlist, char *cmdline);				static int do_error(int n);				static void command_loop(const command_list_t *cmdlist);				static void print_prompt(const command_list_t *cmdlist);								/* read and execute commands until one returns -H_EQUITLOOP */				static void command_loop(const command_list_t *cmdlist)				{					char cmdbuf [MAXLEN];					int n;									do {						if (interactive)							print_prompt(cmdlist);										/* read command */						for (n=0; n < (sizeof cmdbuf)-1; /* nada */) {							char c = hgetchar();							if (c == BS || c == DEL) {								/* backspace and rubout */								if (interactive) {									hputchar(BS);									hputchar(' ');									hputchar(BS);								}								if (n > 0) --n;							} else if (c == CR || c == LF) {								/* end of command line */								break;							} else if (c == '!' || c == '~') {								/* toggle interactive mode */								interactive = (c == '!') ? 1 : 0;								n = 0;								break;							} else if (c == 0x02) {							        /* test mode */								if (interactive) 									hputchar(c);								cmdbuf[n++] = c;							} else if (c < ' ') {								/* control character */								if (interactive) {									hputchar('^');									hputchar(c + '@');								}							} else {								/* ordinary character; echo. */								if (interactive)									hputchar(c);								cmdbuf[n++] = c;							}						}						cmdbuf[n] = '\0';						if (interactive)							hprint("\n");										n = do_command(cmdlist, cmdbuf);						if (!interactive && ((n == 0) || (n == -H_EQUITLOOP)))							hprint("+OK\n");									} while (n != -H_EQUITLOOP);				}								static int do_command(const command_list_t *cmdlist, char *cmdline)				{					char *argv [MAXARGS];					const command_t *cmd;					const abbrev_t *abbr;					char *p;					int argc, n;									/* parse command line; build argv (modifies cmdline) */					p = cmdline;					for (argc=0; argc < MAXARGS; /* nada */) {						while (ISWSP(*p))							++p;						if (*p == '\0')							break;						argv[argc++] = p;						while (*p && !ISWSP(*p))							++p;						if (*p == '\0')							break;						*p++ = '\0';					}					if (!argc)						return 0;									/* find command; test abbrevs first */					cmd = 0;					if (strlen(*argv) == 1) {						for (n=0; (abbr = cmdlist->abbrevs[n]); ++n) {							if (abbr->abbrev == (*argv)[0]) {								cmd = abbr->cmd;								*argv = (char*) cmd->name;								break;							}						}					}					if (!cmd) {						for (n=0; (cmd = cmdlist->commands[n]); ++n) {							if (!strcmp(cmd->name, *argv))								break;						}					}					if (cmd) {						/* invoke command */						errfunc = 0;						errdata.msg = 0;						n = (cmd->func)(argc, argv);					} else						n = -H_ENOCMD;									if (!n)						return 0;					if (n == -H_EQUITLOOP)						return n;					if (n == -H_EUSAGE) {						hprintf("-NG usage: %s %s\n", cmd->name,							cmd->arghelp ? cmd->arghelp : "");						return n;					}									return do_error(n);				}								static int do_error(int n)				{					/* others are all simple or externally defined error messages */					switch ((unsigned char) -n) {					case H_EADDR: errdata.msg = "invalid address"; break;					case H_EALIGN: errdata.msg = "alignment failure"; break;					case H_ECRC: errdata.msg = "CRC mismatch"; break;					case H_EINVAL: errdata.msg = "invalid argument"; break;					case H_EIO: errdata.msg = "I/O error"; break;					case H_ENOCMD: errdata.msg = "command not found"; break;					case H_EOVERFLOW: errdata.msg = "overflow"; break;					case H_EUNDERFLOW: errdata.msg = "underflow"; break;					default:						if (errfunc) {							hprint("-NG ");							(*errfunc)();							hprint("\n");							return n;						}						break;					}					hprintf("-NG %s\n", errdata.msg);					return n;				}								int do_command_loop(command_list_t *cmdlist)				{					cmdlist->prev = top_command_list;					top_command_list = cmdlist;					command_loop(cmdlist);					top_command_list = cmdlist->prev;					return 0;				}								const command_list_t *get_current_commands(void)				{					return top_command_list;				}								static void print_prompt_helper(const command_list_t *cmdlist)				{					if (cmdlist->prev) {						print_prompt_helper(cmdlist->prev);						hprintf(":%s", cmdlist->prompt);					} else						hprint(cmdlist->prompt);				}								static void print_prompt(const command_list_t *cmdlist)				{					print_prompt_helper(cmdlist);					hprint("> ");				}