x86, boot: Carve out early cmdline parsing function

#ifndef _ASM_X86_CMDLINE_H

#define _ASM_X86_CMDLINE_H

int cmdline_find_option_bool(const char *cmdline_ptr, const char *option);

#endif /* _ASM_X86_CMDLINE_H */

obj-$(CONFIG_SMP) += msr-smp.o cache-smp.o

lib-y := delay.o misc.o

lib-y := delay.o misc.o cmdline.o

lib-y += thunk_$(BITS).o

lib-y += usercopy_$(BITS).o usercopy.o getuser.o putuser.o

lib-y += memcpy_$(BITS).o

/*

 * This file is part of the Linux kernel, and is made available under

 * the terms of the GNU General Public License version 2.

 *

 * Misc librarized functions for cmdline poking.

 */

#include <linux/kernel.h>

#include <linux/string.h>

#include <linux/ctype.h>

#include <asm/setup.h>

static inline int myisspace(u8 c)

{

	return c <= ' ';	/* Close enough approximation */

}

/**

 * Find a boolean option (like quiet,noapic,nosmp....)

 *

 * @cmdline: the cmdline string

 * @option: option string to look for

 *

 * Returns the position of that @option (starts counting with 1)

 * or 0 on not found.

 */

int cmdline_find_option_bool(const char *cmdline, const char *option)

{

	char c;

	int len, pos = 0, wstart = 0;

	const char *opptr = NULL;

	enum {

		st_wordstart = 0,	/* Start of word/after whitespace */

		st_wordcmp,	/* Comparing this word */

		st_wordskip,	/* Miscompare, skip */

	} state = st_wordstart;

	if (!cmdline)

		return -1;      /* No command line */

	len = min_t(int, strlen(cmdline), COMMAND_LINE_SIZE);

	if (!len)

		return 0;

	while (len--) {

		c = *(char *)cmdline++;

		pos++;

		switch (state) {

		case st_wordstart:

			if (!c)

				return 0;

			else if (myisspace(c))

				break;

			state = st_wordcmp;

			opptr = option;

			wstart = pos;

			/* fall through */

		case st_wordcmp:

			if (!*opptr)

				if (!c || myisspace(c))

					return wstart;

				else

					state = st_wordskip;

			else if (!c)

				return 0;

			else if (c != *opptr++)

				state = st_wordskip;

			else if (!len)		/* last word and is matching */

				return wstart;

			break;

		case st_wordskip:

			if (!c)

				return 0;

			else if (myisspace(c))

				state = st_wordstart;

			break;

		}

	}

	return 0;	/* Buffer overrun */

}