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/*

 * misc.c

 *

 * This is a collection of several routines from gzip-1.0.3

 * adapted for Linux.

 *

 * malloc by Hannu Savolainen 1993 and Matthias Urlichs 1994

 * puts by Nick Holloway 1993

 */

#include "gzip.h"

#include "lzw.h"

#define EOF -1

DECLARE(uch, inbuf, INBUFSIZ);

DECLARE(uch, outbuf, OUTBUFSIZ+OUTBUF_EXTRA);

DECLARE(uch, window, WSIZE);

unsigned outcnt;

unsigned insize;

unsigned inptr;

extern char input_data[];

extern int input_len;

int input_ptr;

int method, exit_code, part_nb, last_member;

int test = 0;

int force = 0;

int verbose = 1;

long bytes_in, bytes_out;

char *output_data;

unsigned long output_ptr;

extern int end;

long free_mem_ptr = (long)&end;

int to_stdout = 0;

int hard_math = 0;

void (*work)(int inf, int outf);

void makecrc(void);

local int get_method(int);

char *vidmem = (char *)0xC00B8000;

int lines, cols;

int orig_x, orig_y;

void puts(const char *);

void *malloc(int size)

{

        void *p;

        if (size <0) error("Malloc error\n");

        if (free_mem_ptr <= 0) error("Memory error\n");

   while(1) {

        free_mem_ptr = (free_mem_ptr + 3) & ~3; /* Align */

        p = (void *)free_mem_ptr;

        free_mem_ptr += size;

        /*

         * The part of the compressed kernel which has already been expanded

         * is no longer needed. Therefore we can reuse it for malloc.

         * With bigger kernels, this is necessary.

         */

        if (free_mem_ptr < (long)&end) {

                if (free_mem_ptr > (long)&input_data[input_ptr])

                        error("\nOut of memory\n");

                return p;

        }

#if 0   

        if (free_mem_ptr < 0x90000)

#endif  

        return p;

        puts("large kernel, low 1M tight...");

        free_mem_ptr = (long)input_data;

        }

}

void free(void *where)

{       /* Don't care */

}

static void scroll()

{

        int i;

        memcpy ( vidmem, vidmem + cols * 2, ( lines - 1 ) * cols * 2 );

        for ( i = ( lines - 1 ) * cols * 2; i < lines * cols * 2; i += 2 )

                vidmem[i] = ' ';

}

void puts(const char *s)

{

        int x,y;

        char c;

#if 0   

        x = SCREEN_INFO.orig_x;

        y = SCREEN_INFO.orig_y;

#else

        x = orig_x;

        y = orig_y;

#endif  

        while ( ( c = *s++ ) != '\0' ) {

                if ( c == '\n' ) {

                        x = 0;

                        if ( ++y >= lines ) {

                                scroll();

                                y--;

                        }

                } else {

                        vidmem [ ( x + cols * y ) * 2 ] = c;

                        if ( ++x >= cols ) {

                                x = 0;

                                if ( ++y >= lines ) {

                                        scroll();

                                        y--;

                                }

                        }

                }

        }

#if 0   

        SCREEN_INFO.orig_x = x;

        SCREEN_INFO.orig_y = y;

#else

        orig_x = x;

        orig_y = y;

#endif  

}

__ptr_t memset(__ptr_t s, int c, size_t n)

{

        int i;

        char *ss = (char*)s;

        for (i=0;i<n;i++) ss[i] = c;

}

__ptr_t memcpy(__ptr_t __dest, __const __ptr_t __src,

                            size_t __n)

{

        int i;

        char *d = (char *)__dest, *s = (char *)__src;

        for (i=0;i<__n;i++) d[i] = s[i];

}

int memcmp(__ptr_t __dest, __const __ptr_t __src,

                            size_t __n)

{

        int i;

        char *d = (char *)__dest, *s = (char *)__src;

        for (i=0;i<__n;i++, d++, s++)

        {

                if (*d != *s)

                {

                        return (*s - *d);

                }

        }

        return (0);

}

extern ulg crc_32_tab[];   /* crc table, defined below */

/* ===========================================================================

 * Run a set of bytes through the crc shift register.  If s is a NULL

 * pointer, then initialize the crc shift register contents instead.

 * Return the current crc in either case.

 */

ulg updcrc(s, n)

    uch *s;                 /* pointer to bytes to pump through */

    unsigned n;             /* number of bytes in s[] */

{

    register ulg c;         /* temporary variable */

    static ulg crc = (ulg)0xffffffffL; /* shift register contents */

    if (s == NULL) {

        c = 0xffffffffL;

    } else {

        c = crc;

        while (n--) {

            c = crc_32_tab[((int)c ^ (*s++)) & 0xff] ^ (c >> 8);

        }

    }

    crc = c;

    return c ^ 0xffffffffL;       /* (instead of ~c for 64-bit machines) */

}

/* ===========================================================================

 * Clear input and output buffers

 */

void clear_bufs()

{

    outcnt = 0;

    insize = inptr = 0;

    bytes_in = bytes_out = 0L;

}

/* ===========================================================================

 * Fill the input buffer. This is called only when the buffer is empty

 * and at least one byte is really needed.

 */

int fill_inbuf()

{

    int len, i;

    /* Read as much as possible */

puts("*");

    insize = 0;

    do {

        len = INBUFSIZ-insize;

        if (len > (input_len-input_ptr+1)) len=input_len-input_ptr+1;

        if (len == 0 || len == EOF) break;

        for (i=0;i<len;i++) inbuf[insize+i] = input_data[input_ptr+i];

        insize += len;

        input_ptr += len;

    } while (insize < INBUFSIZ);

    if (insize == 0) {

        error("unable to fill buffer\n");

    }

    bytes_in += (ulg)insize;

    inptr = 1;

    return inbuf[0];

}

/* ===========================================================================

 * Write the output window window[0..outcnt-1] and update crc and bytes_out.

 * (Used for the decompressed data only.)

 */

void flush_window()

{

    if (outcnt == 0) return;

    updcrc(window, outcnt);

    memcpy(&output_data[output_ptr], (char *)window, outcnt);

    bytes_out += (ulg)outcnt;

    output_ptr += (ulg)outcnt;

    outcnt = 0;

}

/*

 * Code to compute the CRC-32 table. Borrowed from

 * gzip-1.0.3/makecrc.c.

 */

ulg crc_32_tab[256];

void

makecrc(void)

{

/* Not copyrighted 1990 Mark Adler      */

  unsigned long c;      /* crc shift register */

  unsigned long e;      /* polynomial exclusive-or pattern */

  int i;                /* counter for all possible eight bit values */

  int k;                /* byte being shifted into crc apparatus */

  /* terms of polynomial defining this crc (except x^32): */

  static int p[] = {0,1,2,4,5,7,8,10,11,12,16,22,23,26};

  /* Make exclusive-or pattern from polynomial */

  e = 0;

  for (i = 0; i < sizeof(p)/sizeof(int); i++)

    e |= 1L << (31 - p[i]);

  crc_32_tab[0] = 0;

  for (i = 1; i < 256; i++)

  {

    c = 0;

    for (k = i | 256; k != 1; k >>= 1)

    {

      c = c & 1 ? (c >> 1) ^ e : c >> 1;

      if (k & 1)

        c ^= e;

    }

    crc_32_tab[i] = c;

  }

}

void error(char *x)

{

        puts("\n\n");

        puts(x);

        puts("\n\n -- System halted");

        while(1);       /* Halt */

}

#if 0

#define STACK_SIZE (4096)

long user_stack [STACK_SIZE];

struct {

        long * a;

        short b;

        } stack_start = { & user_stack [STACK_SIZE] , KERNEL_DS };

#endif

void decompress_kernel()

{

#if 0   

        if (SCREEN_INFO.orig_video_mode == 7)

                vidmem = (char *) 0xb0000;

        else

                vidmem = (char *) 0xb8000;

        lines = SCREEN_INFO.orig_video_lines;

        cols = SCREEN_INFO.orig_video_cols;

        if (EXT_MEM_K < 1024) error("<2M of mem\n");

        output_data = (char *)0x100000; /* Points to 1M */

#else

        output_data = (char *)0x0;      /* Points to 0 */

        lines = 25;

        cols = 80;

        orig_x = 0;

        orig_y = 24;

#endif  

        output_ptr = 0;

        exit_code = 0;

        test = 0;

        input_ptr = 0;

        part_nb = 0;

        clear_bufs();

        makecrc();

        puts("Uncompressing Linux...");

        method = get_method(0);

        work(0, 0);

        puts("done.\n");

        puts("Now booting the kernel\n");

}

/* ========================================================================

 * Check the magic number of the input file and update ofname if an

 * original name was given and to_stdout is not set.

 * Return the compression method, -1 for error, -2 for warning.

 * Set inptr to the offset of the next byte to be processed.

 * This function may be called repeatedly for an input file consisting

 * of several contiguous gzip'ed members.

 * IN assertions: there is at least one remaining compressed member.

 *   If the member is a zip file, it must be the only one.

 */

local int get_method(in)

    int in;        /* input file descriptor */

{

    uch flags;

    char magic[2]; /* magic header */

    magic[0] = (char)get_byte();

    magic[1] = (char)get_byte();

    method = -1;                 /* unknown yet */

    part_nb++;                   /* number of parts in gzip file */

    last_member = 0;

    /* assume multiple members in gzip file except for record oriented I/O */

    if (memcmp(magic, GZIP_MAGIC, 2) == 0

        || memcmp(magic, OLD_GZIP_MAGIC, 2) == 0) {

        work = unzip;

        method = (int)get_byte();

        flags  = (uch)get_byte();

        if ((flags & ENCRYPTED) != 0)

            error("Input is encrypted\n");

        if ((flags & CONTINUATION) != 0)

               error("Multi part input\n");

        if ((flags & RESERVED) != 0) {

            error("Input has invalid flags\n");

            exit_code = ERROR;

            if (force <= 1) return -1;

        }

        (ulg)get_byte();        /* Get timestamp */

        ((ulg)get_byte()) << 8;

        ((ulg)get_byte()) << 16;

        ((ulg)get_byte()) << 24;

        (void)get_byte();  /* Ignore extra flags for the moment */

        (void)get_byte();  /* Ignore OS type for the moment */

        if ((flags & EXTRA_FIELD) != 0) {

            unsigned len = (unsigned)get_byte();

            len |= ((unsigned)get_byte())<<8;

            while (len--) (void)get_byte();

        }

        /* Get original file name if it was truncated */

        if ((flags & ORIG_NAME) != 0) {

            if (to_stdout || part_nb > 1) {

                /* Discard the old name */

                while (get_byte() != 0) /* null */ ;

            } else {

            } /* to_stdout */

        } /* orig_name */

        /* Discard file comment if any */

        if ((flags & COMMENT) != 0) {

            while (get_byte() != 0) /* null */ ;

        }

    } else

        error("unknown compression method");

    return method;

}