From: David Laight <david.laight.linux@gmail.com>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Guan-Chun Wu <409411716@gms.tku.edu.tw>,
Kuan-Wei Chiu <visitorckw@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1 1/1] base64: Unroll the tables initialisers
Date: Mon, 3 Nov 2025 22:18:57 +0000 [thread overview]
Message-ID: <20251103221857.1acaf6ab@pumpkin> (raw)
In-Reply-To: <20251103190510.627314-1-andriy.shevchenko@linux.intel.com>
On Mon, 3 Nov 2025 20:05:10 +0100
Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:
> Currently the initialisers of the tables have duplicate indices.
> This prevents from building with `make W=1`.
>
> To address the issue, unroll the table initialisers with generated
> arrays by the following Python excerpt:
>
> CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
>
> def gen_table(ch62, ch63):
> table = [ 0xff ] * 256
> for idx, char in enumerate(CHARS):
> table[ord(char)] = idx
> table[ord(ch62)] = 62
> table[ord(ch63)] = 63
>
> for i in range(0, len(table), 8):
> print (f"\t{', '.join(f"0x{c:02x}" for c in table[i:i+8])},\t/* {i:-3d} - {i+7:-3d} */")
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
> lib/base64.c | 115 +++++++++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 102 insertions(+), 13 deletions(-)
>
> diff --git a/lib/base64.c b/lib/base64.c
> index bcdbd411d63b..0a7c15c5c1b6 100644
> --- a/lib/base64.c
> +++ b/lib/base64.c
> @@ -21,20 +21,109 @@ static const char base64_tables[][65] = {
> [BASE64_IMAP] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,",
> };
>
> -#define BASE64_REV_INIT(ch_62, ch_63) { \
> - [0 ... 255] = -1, \
> - ['A'] = 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, \
> - 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, \
> - ['a'] = 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, \
> - 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, \
> - ['0'] = 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, \
> - [ch_62] = 62, [ch_63] = 63, \
> -}
> -
> static const s8 base64_rev_maps[][256] = {
> - [BASE64_STD] = BASE64_REV_INIT('+', '/'),
> - [BASE64_URLSAFE] = BASE64_REV_INIT('-', '_'),
> - [BASE64_IMAP] = BASE64_REV_INIT('+', ',')
> + [BASE64_STD] = {
> + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 0 - 7 */
You need to use -1 not 0xff.
> + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 8 - 15 */
> + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 16 - 23 */
> + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 24 - 31 */
> + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 32 - 39 */
Nothing wrong with [ 0 ... 39 ] = -1,
> + 0xff, 0xff, 0xff, 0x3e, 0xff, 0xff, 0xff, 0x3f, /* 40 - 47 */
> + 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, /* 48 - 55 */
> + 0x3c, 0x3d, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 56 - 63 */
> + 0xff, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, /* 64 - 71 */
> + 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, /* 72 - 79 */
> + 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, /* 80 - 87 */
> + 0x17, 0x18, 0x19, 0xff, 0xff, 0xff, 0xff, 0xff, /* 88 - 95 */
> + 0xff, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20, /* 96 - 103 */
> + 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, /* 104 - 111 */
> + 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30, /* 112 - 119 */
> + 0x31, 0x32, 0x33, 0xff, 0xff, 0xff, 0xff, 0xff, /* 120 - 127 */
> + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 128 - 135 */
> + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 136 - 143 */
> + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 144 - 151 */
> + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 152 - 159 */
> + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 160 - 167 */
> + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 168 - 175 */
> + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 176 - 183 */
> + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 184 - 191 */
> + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 192 - 199 */
> + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 200 - 207 */
> + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 208 - 215 */
> + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 216 - 223 */
> + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 224 - 231 */
> + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 232 - 239 */
> + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 240 - 247 */
> + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 248 - 255 */
> + },
...
This is impenetrable crap...
David
next prev parent reply other threads:[~2025-11-03 22:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-03 19:05 [PATCH v1 1/1] base64: Unroll the tables initialisers Andy Shevchenko
2025-11-03 19:17 ` Andy Shevchenko
2025-11-03 22:18 ` David Laight [this message]
2025-11-04 8:18 ` Andy Shevchenko
2025-11-04 9:07 ` David Laight
2025-11-04 9:44 ` Andy Shevchenko
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