jpirnayandClaude Sonnet 4.6
e76118dff0
The hot group buffer (formerly up to 50 KB BSS / heap) is removed. During prewarm, each group is now decompressed into a transient malloc that is freed immediately after its glyphs are extracted — only one group buffer and the page buffer coexist at a time. For getBitmap() cache misses (rare: only hit when a glyph wasn't covered by prewarm), the group is also decompressed transiently and freed after the single glyph is compacted into _hotGlyphBuf. Peak heap during prewarm is now: page buffer + one group buffer. Outside of prewarm, heap usage is only the page buffer itself. Works correctly for large future fonts (Vietnamese, CJK) regardless of group size, with no permanent allocation overhead. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
78 lines
2.9 KiB
C++
78 lines
2.9 KiB
C++
#pragma once
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#include <InflateReader.h>
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#include "EpdFontData.h"
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class FontDecompressor {
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public:
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static constexpr uint16_t MAX_PAGE_GLYPHS = 512;
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static constexpr uint8_t MAX_PAGE_SLOTS = 4; // One per font style (R/B/I/BI)
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FontDecompressor() = default;
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~FontDecompressor();
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bool init();
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void deinit();
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// Returns pointer to decompressed bitmap data for the given glyph.
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// Checks the page buffer (from prewarm) first, then falls back to the hot group slot.
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const uint8_t* getBitmap(const EpdFontData* fontData, const EpdGlyph* glyph, uint32_t glyphIndex);
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// Free all cached data (page buffers).
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void clearCache();
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// Pre-scan UTF-8 text and extract needed glyph bitmaps into a flat page buffer.
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// Each group is decompressed once into a temp buffer; only needed glyphs are kept.
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// Returns the number of glyphs that couldn't be loaded (0 on full success).
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int prewarmCache(const EpdFontData* fontData, const char* utf8Text);
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struct Stats {
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uint32_t cacheHits = 0;
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uint32_t cacheMisses = 0;
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uint32_t decompressTimeMs = 0;
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uint16_t uniqueGroupsAccessed = 0;
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uint32_t pageBufferBytes = 0; // pageBuffer allocation
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uint32_t pageGlyphsBytes = 0; // pageGlyphs lookup table allocation
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uint32_t peakTempBytes = 0; // largest temp buffer in prewarm or getBitmap miss
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uint32_t getBitmapTimeUs = 0; // cumulative getBitmap time (micros)
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uint32_t getBitmapCalls = 0; // number of getBitmap calls
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};
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void logStats(const char* label = "FDC");
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void resetStats();
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const Stats& getStats() const { return stats; }
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private:
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Stats stats;
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InflateReader inflateReader;
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// Page buffer slots: each style gets its own flat glyph buffer with sorted lookup.
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// Up to MAX_PAGE_SLOTS (4) styles can be prewarmed simultaneously.
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struct PageGlyphEntry {
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uint32_t glyphIndex;
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uint32_t bufferOffset;
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uint32_t alignedOffset; // byte-aligned offset within its decompressed group (set during prewarm pre-scan)
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};
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struct PageSlot {
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uint8_t* buffer = nullptr;
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const EpdFontData* fontData = nullptr;
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PageGlyphEntry* glyphs = nullptr;
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uint16_t glyphCount = 0;
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};
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PageSlot pageSlots[MAX_PAGE_SLOTS] = {};
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uint8_t pageSlotCount = 0;
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static constexpr uint16_t HOT_GLYPH_BUF_SIZE = 512; // largest packed single glyph
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// Scratch buffer for compacting a single glyph after a getBitmap() miss.
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// Valid until the next getBitmap() call.
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uint8_t _hotGlyphBuf[HOT_GLYPH_BUF_SIZE];
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void freePageBuffer();
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uint16_t getGroupIndex(const EpdFontData* fontData, uint32_t glyphIndex);
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uint32_t getAlignedOffset(const EpdFontData* fontData, uint16_t groupIndex, uint32_t glyphIndex);
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bool decompressGroup(const EpdFontData* fontData, uint16_t groupIndex, uint8_t* outBuf, uint32_t outSize);
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static void compactSingleGlyph(const uint8_t* alignedSrc, uint8_t* packedDst, uint8_t width, uint8_t height);
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static int32_t findGlyphIndex(const EpdFontData* fontData, uint32_t codepoint);
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};
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