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1012-lib-vsprintf-Add-support-for-generic-FOURCCs-by-exte.patch
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1012-lib-vsprintf-Add-support-for-generic-FOURCCs-by-exte.patch
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From f6ab7e4580962c9d82e7dc40dd074d47b2bce034 Mon Sep 17 00:00:00 2001
From: Hector Martin <marcan@marcan.st>
Date: Tue, 1 Feb 2022 00:40:51 +0900
Subject: [PATCH 09/12] lib/vsprintf: Add support for generic FOURCCs by
extending %p4cc
%p4cc is designed for DRM/V4L2 FOURCCs with their specific quirks, but
it's useful to be able to print generic 4-character codes formatted as
an integer. Extend it to add format specifiers for printing generic
32-bit FOURCCs with various endian semantics:
%p4ch Host-endian
%p4cl Little-endian
%p4cb Big-endian
%p4cr Reverse-endian
The endianness determines how bytes are interpreted as a u32, and the
FOURCC is then always printed MSByte-first (this is the opposite of
V4L/DRM FOURCCs). This covers most practical cases, e.g. %p4cr would
allow printing LSByte-first FOURCCs stored in host endian order
(other than the hex form being in character order, not the integer
value).
Signed-off-by: Hector Martin <marcan@marcan.st>
Signed-off-by: Kerem Karabay <kekrby@gmail.com>
---
Documentation/core-api/printk-formats.rst | 32 ++++++++++++++++++++
lib/test_printf.c | 20 +++++++++----
lib/vsprintf.c | 36 +++++++++++++++++++----
scripts/checkpatch.pl | 2 +-
4 files changed, 77 insertions(+), 13 deletions(-)
diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
index dfe7e75a7..0ccef63e6 100644
--- a/Documentation/core-api/printk-formats.rst
+++ b/Documentation/core-api/printk-formats.rst
@@ -631,6 +631,38 @@ Examples::
%p4cc Y10 little-endian (0x20303159)
%p4cc NV12 big-endian (0xb231564e)
+Generic FourCC code
+-------------------
+
+::
+ %p4c[hnbl] gP00 (0x67503030)
+
+Print a generic FourCC code, as both ASCII characters and its numerical
+value as hexadecimal.
+
+The additional ``h``, ``r``, ``b``, and ``l`` specifiers are used to specify
+host, reversed, big or little endian order data respectively. Host endian
+order means the data is interpreted as a 32-bit integer and the most
+significant byte is printed first; that is, the character code as printed
+matches the byte order stored in memory on big-endian systems, and is reversed
+on little-endian systems.
+
+Passed by reference.
+
+Examples for a little-endian machine, given &(u32)0x67503030::
+
+ %p4ch gP00 (0x67503030)
+ %p4cl gP00 (0x67503030)
+ %p4cb 00Pg (0x30305067)
+ %p4cr 00Pg (0x30305067)
+
+Examples for a big-endian machine, given &(u32)0x67503030::
+
+ %p4ch gP00 (0x67503030)
+ %p4cl 00Pg (0x30305067)
+ %p4cb gP00 (0x67503030)
+ %p4cr 00Pg (0x30305067)
+
Rust
----
diff --git a/lib/test_printf.c b/lib/test_printf.c
index 7677ebccf..2355be36f 100644
--- a/lib/test_printf.c
+++ b/lib/test_printf.c
@@ -746,18 +746,26 @@ static void __init fwnode_pointer(void)
static void __init fourcc_pointer(void)
{
struct {
+ char type;
u32 code;
char *str;
} const try[] = {
- { 0x3231564e, "NV12 little-endian (0x3231564e)", },
- { 0xb231564e, "NV12 big-endian (0xb231564e)", },
- { 0x10111213, ".... little-endian (0x10111213)", },
- { 0x20303159, "Y10 little-endian (0x20303159)", },
+ { 'c', 0x3231564e, "NV12 little-endian (0x3231564e)", },
+ { 'c', 0xb231564e, "NV12 big-endian (0xb231564e)", },
+ { 'c', 0x10111213, ".... little-endian (0x10111213)", },
+ { 'c', 0x20303159, "Y10 little-endian (0x20303159)", },
+ { 'h', 0x67503030, "gP00 (0x67503030)", },
+ { 'r', 0x30305067, "gP00 (0x67503030)", },
+ { 'l', cpu_to_le32(0x67503030), "gP00 (0x67503030)", },
+ { 'b', cpu_to_be32(0x67503030), "gP00 (0x67503030)", },
};
unsigned int i;
- for (i = 0; i < ARRAY_SIZE(try); i++)
- test(try[i].str, "%p4cc", &try[i].code);
+ for (i = 0; i < ARRAY_SIZE(try); i++) {
+ char fmt[] = { '%', 'p', '4', 'c', try[i].type, '\0' };
+
+ test(try[i].str, fmt, &try[i].code);
+ }
}
static void __init
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 40f560959..bd9af783c 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1758,27 +1758,50 @@ char *fourcc_string(char *buf, char *end, const u32 *fourcc,
char output[sizeof("0123 little-endian (0x01234567)")];
char *p = output;
unsigned int i;
+ bool pix_fmt = false;
u32 orig, val;
- if (fmt[1] != 'c' || fmt[2] != 'c')
+ if (fmt[1] != 'c')
return error_string(buf, end, "(%p4?)", spec);
if (check_pointer(&buf, end, fourcc, spec))
return buf;
orig = get_unaligned(fourcc);
- val = orig & ~BIT(31);
+ switch (fmt[2]) {
+ case 'h':
+ val = orig;
+ break;
+ case 'r':
+ val = orig = swab32(orig);
+ break;
+ case 'l':
+ val = orig = le32_to_cpu(orig);
+ break;
+ case 'b':
+ val = orig = be32_to_cpu(orig);
+ break;
+ case 'c':
+ /* Pixel formats are printed LSB-first */
+ val = swab32(orig & ~BIT(31));
+ pix_fmt = true;
+ break;
+ default:
+ return error_string(buf, end, "(%p4?)", spec);
+ }
for (i = 0; i < sizeof(u32); i++) {
- unsigned char c = val >> (i * 8);
+ unsigned char c = val >> ((3 - i) * 8);
/* Print non-control ASCII characters as-is, dot otherwise */
*p++ = isascii(c) && isprint(c) ? c : '.';
}
- *p++ = ' ';
- strcpy(p, orig & BIT(31) ? "big-endian" : "little-endian");
- p += strlen(p);
+ if (pix_fmt) {
+ *p++ = ' ';
+ strcpy(p, orig & BIT(31) ? "big-endian" : "little-endian");
+ p += strlen(p);
+ }
*p++ = ' ';
*p++ = '(';
@@ -2348,6 +2371,7 @@ char *rust_fmt_argument(char *buf, char *end, void *ptr);
* read the documentation (path below) first.
* - 'NF' For a netdev_features_t
* - '4cc' V4L2 or DRM FourCC code, with endianness and raw numerical value.
+ * - '4c[hlbr]' Generic FourCC code.
* - 'h[CDN]' For a variable-length buffer, it prints it as a hex string with
* a certain separator (' ' by default):
* C colon
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 880fde13d..f080e33a4 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -6906,7 +6906,7 @@ sub process {
($extension eq "f" &&
defined $qualifier && $qualifier !~ /^w/) ||
($extension eq "4" &&
- defined $qualifier && $qualifier !~ /^cc/)) {
+ defined $qualifier && $qualifier !~ /^c[chlbr]/)) {
$bad_specifier = $specifier;
last;
}
--
2.42.0