From f6ab7e4580962c9d82e7dc40dd074d47b2bce034 Mon Sep 17 00:00:00 2001 From: Hector Martin 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 Signed-off-by: Kerem Karabay --- 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