include: Move ascii85 functions from i915 to linux/ascii85.h

The i915 DRM driver very cleverly used ascii85 encoding for their
GPU state file. Move the encode functions to a general header file to
support other drivers that might be interested in the same
functionality.

v4: Make the return value const char * as suggested by Chris Wilson
v3: Fix error_puts -> err_puts pointed out by the 01.org bot
v2: Update API to be cleaner for the caller as suggested by Chris Wilson

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>
This commit is contained in:
Jordan Crouse
2018-07-24 10:33:19 -06:00
committed by Rob Clark
parent 2f2eb723b5
commit 489cae632f
2 changed files with 42 additions and 30 deletions

38
include/linux/ascii85.h Normal file
View File

@@ -0,0 +1,38 @@
/*
* SPDX-License-Identifier: GPL-2.0
*
* Copyright (c) 2008 Intel Corporation
* Copyright (c) 2018 The Linux Foundation. All rights reserved.
*/
#ifndef _ASCII85_H_
#define _ASCII85_H_
#include <linux/kernel.h>
#define ASCII85_BUFSZ 6
static inline long
ascii85_encode_len(long len)
{
return DIV_ROUND_UP(len, 4);
}
static inline const char *
ascii85_encode(u32 in, char *out)
{
int i;
if (in == 0)
return "z";
out[5] = '\0';
for (i = 5; i--; ) {
out[i] = '!' + in % 85;
in /= 85;
}
return out;
}
#endif