/*
 * 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, better puts by Martin Mares 1995
 * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
 */

/*
 * we have to be careful, because no indirections are allowed here, and
 * paravirt_ops is a kind of one. As it will only run in baremetal anyway,
 * we just keep it from happening
 */
#undef CONFIG_PARAVIRT
#ifdef CONFIG_X86_32
#define _ASM_X86_DESC_H 1
#endif

#ifdef CONFIG_X86_64
#define _LINUX_STRING_H_ 1
#define __LINUX_BITMAP_H 1
#endif

#include <linux/linkage.h>
#include <linux/screen_info.h>
#include <linux/elf.h>
#include <linux/io.h>
#include <asm/page.h>
#include <asm/boot.h>
#include <asm/bootparam.h>

/* WARNING!!
 * This code is compiled with -fPIC and it is relocated dynamically
 * at run time, but no relocation processing is performed.
 * This means that it is not safe to place pointers in static structures.
 */

/*
 * Getting to provable safe in place decompression is hard.
 * Worst case behaviours need to be analyzed.
 * Background information:
 *
 * The file layout is:
 *    magic[2]
 *    method[1]
 *    flags[1]
 *    timestamp[4]
 *    extraflags[1]
 *    os[1]
 *    compressed data blocks[N]
 *    crc[4] orig_len[4]
 *
 * resulting in 18 bytes of non compressed data overhead.
 *
 * Files divided into blocks
 * 1 bit (last block flag)
 * 2 bits (block type)
 *
 * 1 block occurs every 32K -1 bytes or when there 50% compression
 * has been achieved. The smallest block type encoding is always used.
 *
 * stored:
 *    32 bits length in bytes.
 *
 * fixed:
 *    magic fixed tree.
 *    symbols.
 *
 * dynamic:
 *    dynamic tree encoding.
 *    symbols.
 *
 *
 * The buffer for decompression in place is the length of the
 * uncompressed data, plus a small amount extra to keep the algorithm safe.
 * The compressed data is placed at the end of the buffer.  The output
 * pointer is placed at the start of the buffer and the input pointer
 * is placed where the compressed data starts.  Problems will occur
 * when the output pointer overruns the input pointer.
 *
 * The output pointer can only overrun the input pointer if the input
 * pointer is moving faster than the output pointer.  A condition only
 * triggered by data whose compressed form is larger than the uncompressed
 * form.
 *
 * The worst case at the block level is a growth of the compressed data
 * of 5 bytes per 32767 bytes.
 *
 * The worst case internal to a compressed block is very hard to figure.
 * The worst case can at least be boundined by having one bit that represents
 * 32764 bytes and then all of the rest of the bytes representing the very
 * very last byte.
 *
 * All of which is enough to compute an amount of extra data that is required
 * to be safe.  To avoid problems at the block level allocating 5 extra bytes
 * per 32767 bytes of data is sufficient.  To avoind problems internal to a
 * block adding an extra 32767 bytes (the worst case uncompressed block size)
 * is sufficient, to ensure that in the worst case the decompressed data for
 * block will stop the byte before the compressed data for a block begins.
 * To avoid problems with the compressed data's meta information an extra 18
 * bytes are needed.  Leading to the formula:
 *
 * extra_bytes = (uncompressed_size >> 12) + 32768 + 18 + decompressor_size.
 *
 * Adding 8 bytes per 32K is a bit excessive but much easier to calculate.
 * Adding 32768 instead of 32767 just makes for round numbers.
 * Adding the decompressor_size is necessary as it musht live after all
 * of the data as well.  Last I measured the decompressor is about 14K.
 * 10K of actual data and 4K of bss.
 *
 */

/*
 * gzip declarations
 */

#define OF(args)        args
#define STATIC          static

#undef memset
#undef memcpy
#define memzero(s, n)   memset((s), 0, (n))

typedef unsigned char   uch;
typedef unsigned short  ush;
typedef unsigned long   ulg;

/*
 * Window size must be at least 32k, and a power of two.
 * We don't actually have a window just a huge output buffer,
 * so we report a 2G window size, as that should always be
 * larger than our output buffer:
 */
#define WSIZE           0x80000000

/* Input buffer: */
static unsigned char    *inbuf;

/* Sliding window buffer (and final output buffer): */
static unsigned char    *window;

/* Valid bytes in inbuf: */
static unsigned         insize;

/* Index of next byte to be processed in inbuf: */
static unsigned         inptr;

/* Bytes in output buffer: */
static unsigned         outcnt;

/* gzip flag byte */
#define ASCII_FLAG      0x01 /* bit 0 set: file probably ASCII text */
#define CONTINUATION    0x02 /* bit 1 set: continuation of multi-part gz file */
#define EXTRA_FIELD     0x04 /* bit 2 set: extra field present */
#define ORIG_NAM        0x08 /* bit 3 set: original file name present */
#define COMMENT         0x10 /* bit 4 set: file comment present */
#define ENCRYPTED       0x20 /* bit 5 set: file is encrypted */
#define RESERVED        0xC0 /* bit 6, 7:  reserved */

#define get_byte()      (inptr < insize ? inbuf[inptr++] : fill_inbuf())

/* Diagnostic functions */
#ifdef DEBUG
#  define Assert(cond, msg) do { if (!(cond)) error(msg); } while (0)
#  define Trace(x)      do { fprintf x; } while (0)
#  define Tracev(x)     do { if (verbose) fprintf x ; } while (0)
#  define Tracevv(x)    do { if (verbose > 1) fprintf x ; } while (0)
#  define Tracec(c, x)  do { if (verbose && (c)) fprintf x ; } while (0)
#  define Tracecv(c, x) do { if (verbose > 1 && (c)) fprintf x ; } while (0)
#else
#  define Assert(cond, msg)
#  define Trace(x)
#  define Tracev(x)
#  define Tracevv(x)
#  define Tracec(c, x)
#  define Tracecv(c, x)
#endif

static int  fill_inbuf(void);
static void flush_window(void);
static void error(char *m);

/*
 * This is set up by the setup-routine at boot-time
 */
static struct boot_params *real_mode;           /* Pointer to real-mode data */
static int quiet;

extern unsigned char input_data[];
extern int input_len;

static long bytes_out;

static void *memset(void *s, int c, unsigned n);
static void *memcpy(void *dest, const void *src, unsigned n);

static void __putstr(int, const char *);
#define putstr(__x)  __putstr(0, __x)

#ifdef CONFIG_X86_64
#define memptr long
#else
#define memptr unsigned
#endif

static memptr free_mem_ptr;
static memptr free_mem_end_ptr;

static char *vidmem;
static int vidport;
static int lines, cols;

#include "../../../../lib/inflate.c"

static void scroll(void)
{
        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] = ' ';
}

static void __putstr(int error, const char *s)
{
        int x, y, pos;
        char c;

#ifndef CONFIG_X86_VERBOSE_BOOTUP
        if (!error)
                return;
#endif

#ifdef CONFIG_X86_32
        if (real_mode->screen_info.orig_video_mode == 0 &&
            lines == 0 && cols == 0)
                return;
#endif

        x = real_mode->screen_info.orig_x;
        y = real_mode->screen_info.orig_y;

        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--;
                                }
                        }
                }
        }

        real_mode->screen_info.orig_x = x;
        real_mode->screen_info.orig_y = y;

        pos = (x + cols * y) * 2;       /* Update cursor position */
        outb(14, vidport);
        outb(0xff & (pos >> 9), vidport+1);
        outb(15, vidport);
        outb(0xff & (pos >> 1), vidport+1);
}

static void *memset(void *s, int c, unsigned n)
{
        int i;
        char *ss = s;

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

static void *memcpy(void *dest, const void *src, unsigned n)
{
        int i;
        const char *s = src;
        char *d = dest;

        for (i = 0; i < n; i++)
                d[i] = s[i];
        return dest;
}

/* ===========================================================================
 * Fill the input buffer. This is called only when the buffer is empty
 * and at least one byte is really needed.
 */
static int fill_inbuf(void)
{
        error("ran out of input data");
        return 0;
}

/* ===========================================================================
 * Write the output window window[0..outcnt-1] and update crc and bytes_out.
 * (Used for the decompressed data only.)
 */
static void flush_window(void)
{
        /* With my window equal to my output buffer
         * I only need to compute the crc here.
         */
        unsigned long c = crc;         /* temporary variable */
        unsigned n;
        unsigned char *in, ch;

        in = window;
        for (n = 0; n < outcnt; n++) {
                ch = *in++;
                c = crc_32_tab[((int)c ^ ch) & 0xff] ^ (c >> 8);
        }
        crc = c;
        bytes_out += (unsigned long)outcnt;
        outcnt = 0;
}

static void error(char *x)
{
        __putstr(1, "\n\n");
        __putstr(1, x);
        __putstr(1, "\n\n -- System halted");

        while (1)
                asm("hlt");
}

static void parse_elf(void *output)
{
#ifdef CONFIG_X86_64
        Elf64_Ehdr ehdr;
        Elf64_Phdr *phdrs, *phdr;
#else
        Elf32_Ehdr ehdr;
        Elf32_Phdr *phdrs, *phdr;
#endif
        void *dest;
        int i;

        memcpy(&ehdr, output, sizeof(ehdr));
        if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
           ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
           ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
           ehdr.e_ident[EI_MAG3] != ELFMAG3) {
                error("Kernel is not a valid ELF file");
                return;
        }

        if (!quiet)
                putstr("Parsing ELF... ");

        phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
        if (!phdrs)
                error("Failed to allocate space for phdrs");

        memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);

        for (i = 0; i < ehdr.e_phnum; i++) {
                phdr = &phdrs[i];

                switch (phdr->p_type) {
                case PT_LOAD:
#ifdef CONFIG_RELOCATABLE
                        dest = output;
                        dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
#else
                        dest = (void *)(phdr->p_paddr);
#endif
                        memcpy(dest,
                               output + phdr->p_offset,
                               phdr->p_filesz);
                        break;
                default: /* Ignore other PT_* */ break;
                }
        }
}

asmlinkage void decompress_kernel(void *rmode, memptr heap,
                                  unsigned char *input_data,
                                  unsigned long input_len,
                                  unsigned char *output)
{
        real_mode = rmode;

        if (real_mode->hdr.loadflags & QUIET_FLAG)
                quiet = 1;

        if (real_mode->screen_info.orig_video_mode == 7) {
                vidmem = (char *) 0xb0000;
                vidport = 0x3b4;
        } else {
                vidmem = (char *) 0xb8000;
                vidport = 0x3d4;
        }

        lines = real_mode->screen_info.orig_video_lines;
        cols = real_mode->screen_info.orig_video_cols;

        window = output;                /* Output buffer (Normally at 1M) */
        free_mem_ptr     = heap;        /* Heap */
        free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
        inbuf  = input_data;            /* Input buffer */
        insize = input_len;
        inptr  = 0;

#ifdef CONFIG_X86_64
        if ((unsigned long)output & (__KERNEL_ALIGN - 1))
                error("Destination address not 2M aligned");
        if ((unsigned long)output >= 0xffffffffffUL)
                error("Destination address too large");
#else
        if ((u32)output & (CONFIG_PHYSICAL_ALIGN - 1))
                error("Destination address not CONFIG_PHYSICAL_ALIGN aligned");
        if (heap > ((-__PAGE_OFFSET-(512<<20)-1) & 0x7fffffff))
                error("Destination address too large");
#ifndef CONFIG_RELOCATABLE
        if ((u32)output != LOAD_PHYSICAL_ADDR)
                error("Wrong destination address");
#endif
#endif

        makecrc();
        if (!quiet)
                putstr("\nDecompressing Linux... ");
        gunzip();
        parse_elf(output);
        if (!quiet)
                putstr("done.\nBooting the kernel.\n");
        return;
}