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@@ -9,10 +9,95 @@
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* High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
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*/
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+#define _LINUX_STRING_H_ 1
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+#define __LINUX_BITMAP_H 1
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+
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+#include <linux/linkage.h>
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#include <linux/screen_info.h>
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#include <asm/io.h>
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#include <asm/page.h>
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+/* WARNING!!
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+ * This code is compiled with -fPIC and it is relocated dynamically
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+ * at run time, but no relocation processing is performed.
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+ * This means that it is not safe to place pointers in static structures.
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+ */
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+
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+/*
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+ * Getting to provable safe in place decompression is hard.
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+ * Worst case behaviours need to be analized.
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+ * Background information:
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+ *
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+ * The file layout is:
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+ * magic[2]
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+ * method[1]
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+ * flags[1]
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+ * timestamp[4]
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+ * extraflags[1]
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+ * os[1]
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+ * compressed data blocks[N]
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+ * crc[4] orig_len[4]
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+ *
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+ * resulting in 18 bytes of non compressed data overhead.
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+ *
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+ * Files divided into blocks
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+ * 1 bit (last block flag)
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+ * 2 bits (block type)
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+ *
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+ * 1 block occurs every 32K -1 bytes or when there 50% compression has been achieved.
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+ * The smallest block type encoding is always used.
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+ *
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+ * stored:
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+ * 32 bits length in bytes.
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+ *
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+ * fixed:
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+ * magic fixed tree.
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+ * symbols.
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+ *
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+ * dynamic:
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+ * dynamic tree encoding.
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+ * symbols.
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+ *
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+ *
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+ * The buffer for decompression in place is the length of the
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+ * uncompressed data, plus a small amount extra to keep the algorithm safe.
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+ * The compressed data is placed at the end of the buffer. The output
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+ * pointer is placed at the start of the buffer and the input pointer
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+ * is placed where the compressed data starts. Problems will occur
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+ * when the output pointer overruns the input pointer.
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+ *
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+ * The output pointer can only overrun the input pointer if the input
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+ * pointer is moving faster than the output pointer. A condition only
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+ * triggered by data whose compressed form is larger than the uncompressed
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+ * form.
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+ *
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+ * The worst case at the block level is a growth of the compressed data
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+ * of 5 bytes per 32767 bytes.
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+ *
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+ * The worst case internal to a compressed block is very hard to figure.
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+ * The worst case can at least be boundined by having one bit that represents
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+ * 32764 bytes and then all of the rest of the bytes representing the very
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+ * very last byte.
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+ *
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+ * All of which is enough to compute an amount of extra data that is required
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+ * to be safe. To avoid problems at the block level allocating 5 extra bytes
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+ * per 32767 bytes of data is sufficient. To avoind problems internal to a block
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+ * adding an extra 32767 bytes (the worst case uncompressed block size) is
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+ * sufficient, to ensure that in the worst case the decompressed data for
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+ * block will stop the byte before the compressed data for a block begins.
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+ * To avoid problems with the compressed data's meta information an extra 18
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+ * bytes are needed. Leading to the formula:
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+ *
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+ * extra_bytes = (uncompressed_size >> 12) + 32768 + 18 + decompressor_size.
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+ *
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+ * Adding 8 bytes per 32K is a bit excessive but much easier to calculate.
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+ * Adding 32768 instead of 32767 just makes for round numbers.
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+ * Adding the decompressor_size is necessary as it musht live after all
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+ * of the data as well. Last I measured the decompressor is about 14K.
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+ * 10K of actuall data and 4K of bss.
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+ *
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+ */
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+
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/*
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* gzip declarations
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*/
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@@ -28,15 +113,20 @@ typedef unsigned char uch;
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typedef unsigned short ush;
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typedef unsigned long ulg;
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-#define WSIZE 0x8000 /* Window size must be at least 32k, */
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- /* and a power of two */
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+#define WSIZE 0x80000000 /* Window size must be at least 32k,
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+ * and a power of two
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+ * We don't actually have a window just
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+ * a huge output buffer so I report
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+ * a 2G windows size, as that should
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+ * always be larger than our output buffer.
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+ */
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-static uch *inbuf; /* input buffer */
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-static uch window[WSIZE]; /* Sliding window buffer */
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+static uch *inbuf; /* input buffer */
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+static uch *window; /* Sliding window buffer, (and final output buffer) */
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-static unsigned insize = 0; /* valid bytes in inbuf */
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-static unsigned inptr = 0; /* index of next byte to be processed in inbuf */
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-static unsigned outcnt = 0; /* bytes in output buffer */
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+static unsigned insize; /* valid bytes in inbuf */
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+static unsigned inptr; /* index of next byte to be processed in inbuf */
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+static unsigned outcnt; /* bytes in output buffer */
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/* gzip flag byte */
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#define ASCII_FLAG 0x01 /* bit 0 set: file probably ASCII text */
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@@ -87,8 +177,6 @@ extern unsigned char input_data[];
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extern int input_len;
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static long bytes_out = 0;
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-static uch *output_data;
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-static unsigned long output_ptr = 0;
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static void *malloc(int size);
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static void free(void *where);
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@@ -98,17 +186,10 @@ static void *memcpy(void *dest, const void *src, unsigned n);
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static void putstr(const char *);
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-extern int end;
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-static long free_mem_ptr = (long)&end;
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+static long free_mem_ptr;
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static long free_mem_end_ptr;
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-#define INPLACE_MOVE_ROUTINE 0x1000
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-#define LOW_BUFFER_START 0x2000
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-#define LOW_BUFFER_MAX 0x90000
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-#define HEAP_SIZE 0x3000
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-static unsigned int low_buffer_end, low_buffer_size;
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-static int high_loaded =0;
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-static uch *high_buffer_start /* = (uch *)(((ulg)&end) + HEAP_SIZE)*/;
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+#define HEAP_SIZE 0x6000
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static char *vidmem = (char *)0xb8000;
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static int vidport;
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@@ -218,58 +299,31 @@ static void* memcpy(void* dest, const void* src, unsigned n)
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*/
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static int fill_inbuf(void)
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{
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- if (insize != 0) {
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- error("ran out of input data");
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- }
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-
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- inbuf = input_data;
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- insize = input_len;
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- inptr = 1;
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- return inbuf[0];
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+ error("ran out of input data");
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+ return 0;
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}
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/* ===========================================================================
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* Write the output window window[0..outcnt-1] and update crc and bytes_out.
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* (Used for the decompressed data only.)
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*/
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-static void flush_window_low(void)
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-{
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- ulg c = crc; /* temporary variable */
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- unsigned n;
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- uch *in, *out, ch;
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-
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- in = window;
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- out = &output_data[output_ptr];
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- for (n = 0; n < outcnt; n++) {
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- ch = *out++ = *in++;
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- c = crc_32_tab[((int)c ^ ch) & 0xff] ^ (c >> 8);
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- }
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- crc = c;
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- bytes_out += (ulg)outcnt;
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- output_ptr += (ulg)outcnt;
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- outcnt = 0;
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-}
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-
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-static void flush_window_high(void)
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-{
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- ulg c = crc; /* temporary variable */
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- unsigned n;
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- uch *in, ch;
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- in = window;
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- for (n = 0; n < outcnt; n++) {
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- ch = *output_data++ = *in++;
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- if ((ulg)output_data == low_buffer_end) output_data=high_buffer_start;
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- c = crc_32_tab[((int)c ^ ch) & 0xff] ^ (c >> 8);
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- }
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- crc = c;
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- bytes_out += (ulg)outcnt;
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- outcnt = 0;
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-}
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-
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static void flush_window(void)
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{
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- if (high_loaded) flush_window_high();
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- else flush_window_low();
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+ /* With my window equal to my output buffer
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+ * I only need to compute the crc here.
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+ */
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+ ulg c = crc; /* temporary variable */
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+ unsigned n;
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+ uch *in, ch;
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+
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+ in = window;
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+ for (n = 0; n < outcnt; n++) {
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+ ch = *in++;
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+ c = crc_32_tab[((int)c ^ ch) & 0xff] ^ (c >> 8);
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+ }
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+ crc = c;
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+ bytes_out += (ulg)outcnt;
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+ outcnt = 0;
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}
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static void error(char *x)
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@@ -281,57 +335,8 @@ static void error(char *x)
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while(1); /* Halt */
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}
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-static void setup_normal_output_buffer(void)
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-{
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-#ifdef STANDARD_MEMORY_BIOS_CALL
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- if (RM_EXT_MEM_K < 1024) error("Less than 2MB of memory");
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-#else
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- if ((RM_ALT_MEM_K > RM_EXT_MEM_K ? RM_ALT_MEM_K : RM_EXT_MEM_K) < 1024) error("Less than 2MB of memory");
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-#endif
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- output_data = (unsigned char *)__PHYSICAL_START; /* Normally Points to 1M */
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- free_mem_end_ptr = (long)real_mode;
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-}
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-
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-struct moveparams {
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- uch *low_buffer_start; int lcount;
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- uch *high_buffer_start; int hcount;
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-};
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-
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-static void setup_output_buffer_if_we_run_high(struct moveparams *mv)
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-{
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- high_buffer_start = (uch *)(((ulg)&end) + HEAP_SIZE);
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-#ifdef STANDARD_MEMORY_BIOS_CALL
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- if (RM_EXT_MEM_K < (3*1024)) error("Less than 4MB of memory");
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-#else
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- if ((RM_ALT_MEM_K > RM_EXT_MEM_K ? RM_ALT_MEM_K : RM_EXT_MEM_K) < (3*1024)) error("Less than 4MB of memory");
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-#endif
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- mv->low_buffer_start = output_data = (unsigned char *)LOW_BUFFER_START;
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- low_buffer_end = ((unsigned int)real_mode > LOW_BUFFER_MAX
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- ? LOW_BUFFER_MAX : (unsigned int)real_mode) & ~0xfff;
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- low_buffer_size = low_buffer_end - LOW_BUFFER_START;
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- high_loaded = 1;
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- free_mem_end_ptr = (long)high_buffer_start;
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- if ( (__PHYSICAL_START + low_buffer_size) > ((ulg)high_buffer_start)) {
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- high_buffer_start = (uch *)(__PHYSICAL_START + low_buffer_size);
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- mv->hcount = 0; /* say: we need not to move high_buffer */
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- }
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- else mv->hcount = -1;
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- mv->high_buffer_start = high_buffer_start;
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-}
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-
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-static void close_output_buffer_if_we_run_high(struct moveparams *mv)
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-{
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- if (bytes_out > low_buffer_size) {
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- mv->lcount = low_buffer_size;
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- if (mv->hcount)
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- mv->hcount = bytes_out - low_buffer_size;
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- } else {
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- mv->lcount = bytes_out;
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- mv->hcount = 0;
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- }
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-}
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-
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-int decompress_kernel(struct moveparams *mv, void *rmode)
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+asmlinkage void decompress_kernel(void *rmode, unsigned long heap,
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+ uch *input_data, unsigned long input_len, uch *output)
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{
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real_mode = rmode;
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@@ -346,13 +351,21 @@ int decompress_kernel(struct moveparams *mv, void *rmode)
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lines = RM_SCREEN_INFO.orig_video_lines;
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cols = RM_SCREEN_INFO.orig_video_cols;
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- if (free_mem_ptr < 0x100000) setup_normal_output_buffer();
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- else setup_output_buffer_if_we_run_high(mv);
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+ window = output; /* Output buffer (Normally at 1M) */
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+ free_mem_ptr = heap; /* Heap */
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+ free_mem_end_ptr = heap + HEAP_SIZE;
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+ inbuf = input_data; /* Input buffer */
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+ insize = input_len;
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+ inptr = 0;
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+
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+ if ((ulg)output & 0x1fffffUL)
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+ error("Destination address not 2M aligned");
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+ if ((ulg)output >= 0xffffffffffUL)
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+ error("Destination address too large");
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makecrc();
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putstr(".\nDecompressing Linux...");
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gunzip();
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putstr("done.\nBooting the kernel.\n");
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- if (high_loaded) close_output_buffer_if_we_run_high(mv);
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- return high_loaded;
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+ return;
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}
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Vivek Goyal