From 2f5c48d0b2b0e6f1dd5681bb18aef868914624bd Mon Sep 17 00:00:00 2001
From: Myles Watson <mylesgw@gmail.com>
Date: Fri, 15 Feb 2008 19:27:13 +0000
Subject: [PATCH] This patch adds zero compression for bss segments.  One of
 the reasons for this is that currently, if you select no compression, the bss
 segment of filo takes up 153K with just zeroes.  With this patch, it always
 takes up a lar header + 1 byte.  I left the one byte so that the checksum
 wouldn't be broken.

This patch could have taken out the calloc in the compression area,
but since it only uses compile-time memory, I decided to keep this
simple.

Myles

Signed-off-by: Myles Watson <myles@pel.cs.byu.edu>
Acked-by: Ronald G. Minnich <rminnich@gmail.com>


git-svn-id: svn://coreboot.org/repository/coreboot-v3@601 f3766cd6-281f-0410-b1cd-43a5c92072e9
---
 include/lar.h     |  1 +
 lib/lar.c         |  5 +++++
 util/lar/lar.h    |  8 +++++++-
 util/lar/lib.c    | 19 +++++++++++++++++++
 util/lar/stream.c |  2 +-
 5 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/include/lar.h b/include/lar.h
index 95b411a6cc..9b0914023a 100644
--- a/include/lar.h
+++ b/include/lar.h
@@ -67,6 +67,7 @@ struct lar_header {
 	 * 0 = no compression
 	 * 1 = lzma
 	 * 2 = nrv2b
+	 * 3 = zeroes
 	 */
 	u32 compression;
 	u64 entry;
diff --git a/lib/lar.c b/lib/lar.c
index 3eb1fccbd8..325a3e1517 100644
--- a/lib/lar.c
+++ b/lib/lar.c
@@ -170,6 +170,11 @@ int process_file(const struct mem_file *archive, void *where)
 		return 0;
 	}
 #endif
+	/* zeroes */
+	if (archive->compression == 3) {
+		memset(archive->start, 0, archive->reallen);
+		return 0;
+	}
 	printk(BIOS_INFO, "LAR: Compression algorithm #%i not supported!\n", archive->compression);
 	return -1;
 }
diff --git a/util/lar/lar.h b/util/lar/lar.h
index 42c9a2c271..28e670fa33 100644
--- a/util/lar/lar.h
+++ b/util/lar/lar.h
@@ -75,6 +75,7 @@ struct lar_header {
 	 * 0 = no compression
 	 * 1 = lzma
 	 * 2 = nrv2b
+	 * 3 = zeroes
 	 */
 	u32 compression;
 	u64 entry;
@@ -91,7 +92,7 @@ struct lar {
 	u32 size; /**< Size of the mmaped file */
 };
 
-enum compalgo { none = 0, lzma = 1, nrv2b = 2 };
+enum compalgo { none = 0, lzma = 1, nrv2b = 2, zeroes = 3 };
 
 typedef void (*compress_func) (char *, int, char *, int *);
 typedef void (*uncompress_func) (char *, int, char *, int);
@@ -100,26 +101,31 @@ void compress_impossible(char *in, int in_len, char *out, int *out_len);
 void do_no_compress(char *in, int in_len, char *out, int *out_len);
 void do_lzma_compress(char *in, int in_len, char *out, int *out_len);
 void do_nrv2b_compress(char *in, int in_len, char *out, int *out_len);
+void do_zeroes_compress(char *in, int in_len, char *out, int *out_len);
 
 void uncompress_impossible(char *dst, int dst_len, char *src, int src_len);
 void do_no_uncompress(char *dst, int dst_len, char *src, int src_len);
 void do_lzma_uncompress(char *dst, int dst_len, char *src, int src_len);
 void do_nrv2b_uncompress(char *dst, int dst_len, char *src, int src_len);
+void do_zeroes_uncompress(char *dst, int dst_len, char *src, int src_len);
 
 static compress_func compress_functions[] = {
 	do_no_compress,
 	do_lzma_compress,
 	do_nrv2b_compress,
+	do_zeroes_compress,
 };
 
 static uncompress_func uncompress_functions[] = {
 	do_no_uncompress,
 	do_lzma_uncompress,
 	do_nrv2b_uncompress,
+	do_zeroes_uncompress,
 };
 
 static const char *algo_name[] = {
 	"",
 	"lzma",
 	"nrv2b",
+	"zeroes",
 };
diff --git a/util/lar/lib.c b/util/lar/lib.c
index d9388c64f6..0dd2a69663 100644
--- a/util/lar/lib.c
+++ b/util/lar/lib.c
@@ -56,6 +56,25 @@ void do_no_compress(char *in, int in_len, char *out, int *out_len)
 	out_len[0] = in_len;
 }
 
+/**
+ * The zeroes "compress" hook
+ * Leave one byte for calculating the checksum.
+ */
+void do_zeroes_compress(char *in, int in_len, char *out, int *out_len)
+{
+	out[0] = 0;
+	out_len[0] = 1;
+}
+
+/**
+ * The zeroes "uncompress" hook
+ */
+
+void do_zeroes_uncompress(char *dst, int dst_len, char *src, int src_len)
+{
+	memset(dst, 0, dst_len);
+}
+
 /**
  * The default "uncompress" hook to call when no other compression is used
  */
diff --git a/util/lar/stream.c b/util/lar/stream.c
index 5439b23df3..0b9f766189 100644
--- a/util/lar/stream.c
+++ b/util/lar/stream.c
@@ -147,7 +147,7 @@ int output_elf_segments(struct lar *lar, char *name, char *filebuf,
 				fprintf(stderr, "Dropping empty section\n");
 			continue;
 		}
-		thisalgo = algo;
+		thisalgo = zeroes;
 		if (verbose())
 			fprintf(stderr,  "New section addr %#x size %#x\n",
 			(u32)shdr[i].sh_addr, (u32)shdr[i].sh_size);