--- /dev/null
+/*
+ * 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
+ */
+
+#define _LWK_STRING_H 1
+#define _LWK_BITMAP_H 1
+
+#include <lwk/linkage.h>
+#include <lwk/screen_info.h>
+#include <arch/page.h>
+#include <arch/io.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 analized.
+ * 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 actuall 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;
+
+#define WSIZE 0x80000000 /* 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 I report
+ * a 2G windows size, as that should
+ * always be larger than our output buffer.
+ */
+
+static uch *inbuf; /* input buffer */
+static uch *window; /* Sliding window buffer, (and final output buffer) */
+
+static unsigned insize; /* valid bytes in inbuf */
+static unsigned inptr; /* index of next byte to be processed in inbuf */
+static unsigned outcnt; /* bytes in output buffer */
+
+/* gzip flag byte */
+#define ASCII_FLAG 0x01 /* bit 0 set: file probably ASCII text */
+#define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
+#define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
+#define ORIG_NAME 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) {if(!(cond)) error(msg);}
+# define Trace(x) fprintf x
+# define Tracev(x) {if (verbose) fprintf x ;}
+# define Tracevv(x) {if (verbose>1) fprintf x ;}
+# define Tracec(c,x) {if (verbose && (c)) fprintf x ;}
+# define Tracecv(c,x) {if (verbose>1 && (c)) fprintf x ;}
+#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);
+static void gzip_mark(void **);
+static void gzip_release(void **);
+
+/*
+ * This is set up by the setup-routine at boot-time
+ */
+static unsigned char *real_mode; /* Pointer to real-mode data */
+
+#define RM_EXT_MEM_K (*(unsigned short *)(real_mode + 0x2))
+#ifndef STANDARD_MEMORY_BIOS_CALL
+#define RM_ALT_MEM_K (*(unsigned long *)(real_mode + 0x1e0))
+#endif
+#define RM_SCREEN_INFO (*(struct screen_info *)(real_mode+0))
+
+extern unsigned char input_data[];
+extern int input_len;
+
+static long bytes_out = 0;
+
+static void *malloc(int size);
+static void free(void *where);
+
+static void *memset(void *s, int c, unsigned n);
+static void *memcpy(void *dest, const void *src, unsigned n);
+
+static void putstr(const char *);
+
+static long free_mem_ptr;
+static long free_mem_end_ptr;
+
+#define HEAP_SIZE 0x7000
+
+static char *vidmem = (char *)0xb8000;
+static int vidport;
+static int lines, cols;
+
+#include "../../../../lib/inflate.c"
+
+static void *malloc(int size)
+{
+ void *p;
+
+ if (size <0) error("Malloc error");
+ if (free_mem_ptr <= 0) error("Memory error");
+
+ free_mem_ptr = (free_mem_ptr + 3) & ~3; /* Align */
+
+ p = (void *)free_mem_ptr;
+ free_mem_ptr += size;
+
+ if (free_mem_ptr >= free_mem_end_ptr)
+ error("Out of memory");
+
+ return p;
+}
+
+static void free(void *where)
+{ /* Don't care */
+}
+
+static void gzip_mark(void **ptr)
+{
+ *ptr = (void *) free_mem_ptr;
+}
+
+static void gzip_release(void **ptr)
+{
+ free_mem_ptr = (long) *ptr;
+}
+
+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(const char *s)
+{
+ int x,y,pos;
+ char c;
+
+ x = RM_SCREEN_INFO.orig_x;
+ y = RM_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--;
+ }
+ }
+ }
+ }
+
+ RM_SCREEN_INFO.orig_x = x;
+ RM_SCREEN_INFO.orig_y = y;
+
+ pos = (x + cols * y) * 2; /* Update cursor position */
+ outb_p(14, vidport);
+ outb_p(0xff & (pos >> 9), vidport+1);
+ outb_p(15, vidport);
+ outb_p(0xff & (pos >> 1), vidport+1);
+}
+
+static void* memset(void* s, int c, unsigned n)
+{
+ int i;
+ char *ss = (char*)s;
+
+ for (i=0;i<n;i++) ss[i] = c;
+ return s;
+}
+
+static void* memcpy(void* dest, const void* src, unsigned n)
+{
+ int i;
+ char *d = (char *)dest, *s = (char *)src;
+
+ 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.
+ */
+ ulg c = crc; /* temporary variable */
+ unsigned n;
+ uch *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 += (ulg)outcnt;
+ outcnt = 0;
+}
+
+static void error(char *x)
+{
+ putstr("\n\n");
+ putstr(x);
+ putstr("\n\n -- System halted");
+
+ while(1); /* Halt */
+}
+
+asmlinkage void decompress_kernel(void *rmode, unsigned long heap,
+ uch *input_data, unsigned long input_len, uch *output)
+{
+ real_mode = rmode;
+
+ if (RM_SCREEN_INFO.orig_video_mode == 7) {
+ vidmem = (char *) 0xb0000;
+ vidport = 0x3b4;
+ } else {
+ vidmem = (char *) 0xb8000;
+ vidport = 0x3d4;
+ }
+
+ lines = RM_SCREEN_INFO.orig_video_lines;
+ cols = RM_SCREEN_INFO.orig_video_cols;
+
+ window = output; /* Output buffer (Normally at 1M) */
+ free_mem_ptr = heap; /* Heap */
+ free_mem_end_ptr = heap + HEAP_SIZE;
+ inbuf = input_data; /* Input buffer */
+ insize = input_len;
+ inptr = 0;
+
+ if ((ulg)output & (__KERNEL_ALIGN - 1))
+ error("Destination address not 2M aligned");
+ if ((ulg)output >= 0xffffffffffUL)
+ error("Destination address too large");
+
+ makecrc();
+ putstr(".\nDecompressing LWK...");
+ gunzip();
+ putstr("done.\nBooting the kernel.\n");
+ return;
+}
