From: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
To: ffmpeg-devel@ffmpeg.org
Cc: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Subject: [FFmpeg-devel] [PATCH] avcodec/ccaption_dec: Avoid relocations for strings
Date: Tue, 5 Mar 2024 21:29:53 +0100
Message-ID: <AS8P250MB07446AE07339477C060B599E8F222@AS8P250MB0744.EURP250.PROD.OUTLOOK.COM> (raw)
The longest string here takes four bytes, so using an array
of pointers is wasteful even when ignoring the cost of relocations;
the lack of relocations also implies that this array
will now be put into .rodata and not into .data.rel.ro.
Static asserts are used to ensure that all strings are always
properly zero-terminated.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
---
Now using static asserts to address the main point of
criticism in https://patchwork.ffmpeg.org/project/ffmpeg/patch/20210106081702.2495510-1-andreas.rheinhardt@gmail.com/
libavcodec/ccaption_dec.c | 215 ++++++++++++++++++++------------------
1 file changed, 115 insertions(+), 100 deletions(-)
diff --git a/libavcodec/ccaption_dec.c b/libavcodec/ccaption_dec.c
index 95143e7e46..1550e4b253 100644
--- a/libavcodec/ccaption_dec.c
+++ b/libavcodec/ccaption_dec.c
@@ -67,108 +67,123 @@ enum cc_charset {
CCSET_EXTENDED_PORTUGUESE_GERMAN_DANISH,
};
-static const char *charset_overrides[4][128] =
+#define CHARSET_OVERRIDE_LIST(START_SET, ENTRY, END_SET) \
+ START_SET(CCSET_BASIC_AMERICAN) \
+ ENTRY(0x27, "\u2019") \
+ ENTRY(0x2a, "\u00e1") \
+ ENTRY(0x5c, "\u00e9") \
+ ENTRY(0x5e, "\u00ed") \
+ ENTRY(0x5f, "\u00f3") \
+ ENTRY(0x60, "\u00fa") \
+ ENTRY(0x7b, "\u00e7") \
+ ENTRY(0x7c, "\u00f7") \
+ ENTRY(0x7d, "\u00d1") \
+ ENTRY(0x7e, "\u00f1") \
+ ENTRY(0x7f, "\u2588") \
+ END_SET \
+ START_SET(CCSET_SPECIAL_AMERICAN) \
+ ENTRY(0x30, "\u00ae") \
+ ENTRY(0x31, "\u00b0") \
+ ENTRY(0x32, "\u00bd") \
+ ENTRY(0x33, "\u00bf") \
+ ENTRY(0x34, "\u2122") \
+ ENTRY(0x35, "\u00a2") \
+ ENTRY(0x36, "\u00a3") \
+ ENTRY(0x37, "\u266a") \
+ ENTRY(0x38, "\u00e0") \
+ ENTRY(0x39, "\u00A0") \
+ ENTRY(0x3a, "\u00e8") \
+ ENTRY(0x3b, "\u00e2") \
+ ENTRY(0x3c, "\u00ea") \
+ ENTRY(0x3d, "\u00ee") \
+ ENTRY(0x3e, "\u00f4") \
+ ENTRY(0x3f, "\u00fb") \
+ END_SET \
+ START_SET(CCSET_EXTENDED_SPANISH_FRENCH_MISC) \
+ ENTRY(0x20, "\u00c1") \
+ ENTRY(0x21, "\u00c9") \
+ ENTRY(0x22, "\u00d3") \
+ ENTRY(0x23, "\u00da") \
+ ENTRY(0x24, "\u00dc") \
+ ENTRY(0x25, "\u00fc") \
+ ENTRY(0x26, "\u00b4") \
+ ENTRY(0x27, "\u00a1") \
+ ENTRY(0x28, "*") \
+ ENTRY(0x29, "\u2018") \
+ ENTRY(0x2a, "-") \
+ ENTRY(0x2b, "\u00a9") \
+ ENTRY(0x2c, "\u2120") \
+ ENTRY(0x2d, "\u00b7") \
+ ENTRY(0x2e, "\u201c") \
+ ENTRY(0x2f, "\u201d") \
+ ENTRY(0x30, "\u00c0") \
+ ENTRY(0x31, "\u00c2") \
+ ENTRY(0x32, "\u00c7") \
+ ENTRY(0x33, "\u00c8") \
+ ENTRY(0x34, "\u00ca") \
+ ENTRY(0x35, "\u00cb") \
+ ENTRY(0x36, "\u00eb") \
+ ENTRY(0x37, "\u00ce") \
+ ENTRY(0x38, "\u00cf") \
+ ENTRY(0x39, "\u00ef") \
+ ENTRY(0x3a, "\u00d4") \
+ ENTRY(0x3b, "\u00d9") \
+ ENTRY(0x3c, "\u00f9") \
+ ENTRY(0x3d, "\u00db") \
+ ENTRY(0x3e, "\u00ab") \
+ ENTRY(0x3f, "\u00bb") \
+ END_SET \
+ START_SET(CCSET_EXTENDED_PORTUGUESE_GERMAN_DANISH) \
+ ENTRY(0x20, "\u00c3") \
+ ENTRY(0x21, "\u00e3") \
+ ENTRY(0x22, "\u00cd") \
+ ENTRY(0x23, "\u00cc") \
+ ENTRY(0x24, "\u00ec") \
+ ENTRY(0x25, "\u00d2") \
+ ENTRY(0x26, "\u00f2") \
+ ENTRY(0x27, "\u00d5") \
+ ENTRY(0x28, "\u00f5") \
+ ENTRY(0x29, "{") \
+ ENTRY(0x2a, "}") \
+ ENTRY(0x2b, "\\") \
+ ENTRY(0x2c, "^") \
+ ENTRY(0x2d, "_") \
+ ENTRY(0x2e, "|") \
+ ENTRY(0x2f, "~") \
+ ENTRY(0x30, "\u00c4") \
+ ENTRY(0x31, "\u00e4") \
+ ENTRY(0x32, "\u00d6") \
+ ENTRY(0x33, "\u00f6") \
+ ENTRY(0x34, "\u00df") \
+ ENTRY(0x35, "\u00a5") \
+ ENTRY(0x36, "\u00a4") \
+ ENTRY(0x37, "\u00a6") \
+ ENTRY(0x38, "\u00c5") \
+ ENTRY(0x39, "\u00e5") \
+ ENTRY(0x3a, "\u00d8") \
+ ENTRY(0x3b, "\u00f8") \
+ ENTRY(0x3c, "\u250c") \
+ ENTRY(0x3d, "\u2510") \
+ ENTRY(0x3e, "\u2514") \
+ ENTRY(0x3f, "\u2518") \
+ END_SET \
+
+static const char charset_overrides[4][128][sizeof("\u266a")] =
{
- [CCSET_BASIC_AMERICAN] = {
- [0x27] = "\u2019",
- [0x2a] = "\u00e1",
- [0x5c] = "\u00e9",
- [0x5e] = "\u00ed",
- [0x5f] = "\u00f3",
- [0x60] = "\u00fa",
- [0x7b] = "\u00e7",
- [0x7c] = "\u00f7",
- [0x7d] = "\u00d1",
- [0x7e] = "\u00f1",
- [0x7f] = "\u2588"
- },
- [CCSET_SPECIAL_AMERICAN] = {
- [0x30] = "\u00ae",
- [0x31] = "\u00b0",
- [0x32] = "\u00bd",
- [0x33] = "\u00bf",
- [0x34] = "\u2122",
- [0x35] = "\u00a2",
- [0x36] = "\u00a3",
- [0x37] = "\u266a",
- [0x38] = "\u00e0",
- [0x39] = "\u00A0",
- [0x3a] = "\u00e8",
- [0x3b] = "\u00e2",
- [0x3c] = "\u00ea",
- [0x3d] = "\u00ee",
- [0x3e] = "\u00f4",
- [0x3f] = "\u00fb",
- },
- [CCSET_EXTENDED_SPANISH_FRENCH_MISC] = {
- [0x20] = "\u00c1",
- [0x21] = "\u00c9",
- [0x22] = "\u00d3",
- [0x23] = "\u00da",
- [0x24] = "\u00dc",
- [0x25] = "\u00fc",
- [0x26] = "\u00b4",
- [0x27] = "\u00a1",
- [0x28] = "*",
- [0x29] = "\u2018",
- [0x2a] = "-",
- [0x2b] = "\u00a9",
- [0x2c] = "\u2120",
- [0x2d] = "\u00b7",
- [0x2e] = "\u201c",
- [0x2f] = "\u201d",
- [0x30] = "\u00c0",
- [0x31] = "\u00c2",
- [0x32] = "\u00c7",
- [0x33] = "\u00c8",
- [0x34] = "\u00ca",
- [0x35] = "\u00cb",
- [0x36] = "\u00eb",
- [0x37] = "\u00ce",
- [0x38] = "\u00cf",
- [0x39] = "\u00ef",
- [0x3a] = "\u00d4",
- [0x3b] = "\u00d9",
- [0x3c] = "\u00f9",
- [0x3d] = "\u00db",
- [0x3e] = "\u00ab",
- [0x3f] = "\u00bb",
- },
- [CCSET_EXTENDED_PORTUGUESE_GERMAN_DANISH] = {
- [0x20] = "\u00c3",
- [0x21] = "\u00e3",
- [0x22] = "\u00cd",
- [0x23] = "\u00cc",
- [0x24] = "\u00ec",
- [0x25] = "\u00d2",
- [0x26] = "\u00f2",
- [0x27] = "\u00d5",
- [0x28] = "\u00f5",
- [0x29] = "{",
- [0x2a] = "}",
- [0x2b] = "\\",
- [0x2c] = "^",
- [0x2d] = "_",
- [0x2e] = "|",
- [0x2f] = "~",
- [0x30] = "\u00c4",
- [0x31] = "\u00e4",
- [0x32] = "\u00d6",
- [0x33] = "\u00f6",
- [0x34] = "\u00df",
- [0x35] = "\u00a5",
- [0x36] = "\u00a4",
- [0x37] = "\u00a6",
- [0x38] = "\u00c5",
- [0x39] = "\u00e5",
- [0x3a] = "\u00d8",
- [0x3b] = "\u00f8",
- [0x3c] = "\u250c",
- [0x3d] = "\u2510",
- [0x3e] = "\u2514",
- [0x3f] = "\u2518",
+#define START_SET(IDX) \
+ [IDX] = {
+#define ENTRY(idx, string) \
+ [idx] = string,
+#define END_SET \
},
+ CHARSET_OVERRIDE_LIST(START_SET, ENTRY, END_SET)
};
+#define EMPTY_START(IDX)
+#define EMPTY_END
+#define ASSERT_ENTRY(IDX, str) \
+ _Static_assert(sizeof(str) <= sizeof(charset_overrides[0][0]), \
+ "'" str "' string takes too much space");
+CHARSET_OVERRIDE_LIST(EMPTY_START, ASSERT_ENTRY, EMPTY_END)
static const unsigned char bg_attribs[8] = // Color
{
@@ -571,7 +586,7 @@ static int capture_screen(CCaptionSubContext *ctx)
prev_color = color[j];
prev_bg_color = bg[j];
override = charset_overrides[(int)charset[j]][(int)row[j]];
- if (override) {
+ if (override[0]) {
av_bprintf(&ctx->buffer[bidx], "%s%s%s%s%s", e_tag, s_tag, c_tag, b_tag, override);
seen_char = 1;
} else if (row[j] == ' ' && !seen_char) {
--
2.40.1
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
To unsubscribe, visit link above, or email
ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
next reply other threads:[~2024-03-05 20:30 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-05 20:29 Andreas Rheinhardt [this message]
2024-03-05 20:56 ` Marth64
2024-03-07 8:13 ` Andreas Rheinhardt
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=AS8P250MB07446AE07339477C060B599E8F222@AS8P250MB0744.EURP250.PROD.OUTLOOK.COM \
--to=andreas.rheinhardt@outlook.com \
--cc=ffmpeg-devel@ffmpeg.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Git Inbox Mirror of the ffmpeg-devel mailing list - see https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
This inbox may be cloned and mirrored by anyone:
git clone --mirror https://master.gitmailbox.com/ffmpegdev/0 ffmpegdev/git/0.git
# If you have public-inbox 1.1+ installed, you may
# initialize and index your mirror using the following commands:
public-inbox-init -V2 ffmpegdev ffmpegdev/ https://master.gitmailbox.com/ffmpegdev \
ffmpegdev@gitmailbox.com
public-inbox-index ffmpegdev
Example config snippet for mirrors.
AGPL code for this site: git clone https://public-inbox.org/public-inbox.git