3f453d0110
The stb_truetype library performs around 5 allocations per character rendered, totalling approximately 26KB of temporary memory. This creates significant malloc/free overhead and heap fragmentation. Add a scratch buffer mechanism that pre-allocates memory once during probe and reuses it for each character. The buffer is reset at the start of each putc_xy() call, and allocations come from this buffer using a simple bump allocator with 8-byte alignment. If the scratch buffer is exhausted (e.g. for very complex glyphs), the allocator falls back to malloc transparently. The scratch buffer is controlled by two new Kconfig options: - CONSOLE_TRUETYPE_SCRATCH: Enable/disable the feature (default y) - CONSOLE_TRUETYPE_SCRATCH_SIZE: Buffer size in bytes (default 32KB) Co-developed-by: Claude <noreply@anthropic.com> Signed-off-by: Simon Glass <simon.glass@canonical.com>
104 lines
2.4 KiB
ReStructuredText
104 lines
2.4 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0+:
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.. index::
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single: font (command)
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font command
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============
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Synopsis
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--------
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::
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font list
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font select [<name> [<size>]]
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font size [<size>]
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font info
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Description
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-----------
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The *font* command allows selection of the font to use on the video console.
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This is available when the TrueType console is in use.
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font list
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~~~~~~~~~
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This lists the available fonts, using the name of the font file in the build.
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Any enabled bitmap fonts are listed as well.
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font select
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~~~~~~~~~~~
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This selects a new font and optionally changes the size. If the name is not
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provided, the default font is used.
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font size
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~~~~~~~~~
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This changes the font size only. With no argument it shows the current size.
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font info
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~~~~~~~~~
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This shows glyph rendering statistics, specifically the number of glyphs
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rendered since the video console was set up.
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This subcommand requires CONFIG_VIDEO_GLYPH_STATS=y.
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Examples
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--------
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::
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=> font list
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nimbus_sans_l_regular
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cantoraone_regular
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=> font size
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30
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=> font size 40
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=> font select cantoraone_regular 20
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=>
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This shows an example of selecting a bitmap font when Truetype is active::
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=> font list
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8x16
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12x22
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nimbus_sans_l_regular
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cantoraone_regular
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=> font sel 8x16
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This shows glyph rendering statistics::
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=> font info
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glyphs rendered: 32705
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Configuration
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-------------
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The command is only available if CONFIG_CONSOLE_TRUETYPE=y.
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CONFIG_CONSOLE_TRUETYPE_GLYPH_BUF enables a pre-allocated buffer for glyph
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rendering, avoiding malloc/free per character. The buffer starts at 4KB and
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grows as needed via realloc().
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CONFIG_CONSOLE_TRUETYPE_SCRATCH enables a scratch buffer for internal stbtt
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allocations. Without this, the TrueType library performs around 5 allocations
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per character (totalling ~26KB), creating malloc/free overhead and heap
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fragmentation. With the scratch buffer, memory is allocated once at probe time
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and reused for each character. CONFIG_CONSOLE_TRUETYPE_SCRATCH_SIZE sets the
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buffer size (default 32KB), which is sufficient for most Latin characters.
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Complex glyphs (CJK, emoji) or very large font sizes may need 64KB or more.
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Allocations exceeding the buffer size fall back to malloc transparently.
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CONFIG_VIDEO_GLYPH_STATS enables tracking of glyph-rendering statistics.
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Return value
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------------
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The return value $? is 0 (true) if the command completes.
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The return value is 1 (false) if the command fails.
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