Robert Allan JamesandClaude Opus 5
f81e9c92bc
fb_scroll_rows() hardcoded the pixel distance it physically shifts the framebuffer by as char_rows * 16 * scale -- the bitmap-font (font_8x16.c) cell height -- regardless of which glyph mode vt100.c actually had active. In TTF mode (the REPL's default, cell height 24px via VT100_TTF_CELL_H_PX) this meant every scroll_up(1) call physically shifted the framebuffer by only 16px while the text model (g_vt.rows, py_of()) placed each row 24px apart. That 8px-per-scroll shortfall compounds with every subsequent scroll: a few scrolls barely show it, but enough scrolls -- or scrolling quickly, which is just many scrolls in a short span -- accumulates into visible pixel overlap between rows, with newer lines drawn on top of the tail end of older ones. fb_scroll_rect() (the box-confined scroll added later for 4.4t) already carried a doc comment calling this out explicitly, describing its own explicit pixel_rows parameter as the fix for fb_scroll_rows()'s "fixed 16px-row assumption" -- fb_scroll_rows() itself was just never updated to match. Fixed by changing fb_scroll_rows()'s parameter from an implicit char_rows count to an explicit pixel_rows count (matching fb_scroll_rect()'s existing convention), and having its one caller (vt100.c's scroll_up()) pass lines * cell_h() -- the real active cell height -- instead of a raw line count for the callee to guess at. Verified: booted amd64 to the REPL (TTF mode active per sk_repl()'s own console_fb_enable_ttf() call), let boot chatter + WORDS output scroll the screen through thousands of accumulated scroll_up() calls, then measured every visible line's y-position via a QMP screendump. Spacing held at a perfectly consistent 24px (TTF cell height) top to bottom with zero drift -- the old hardcoded-16px bug could not have produced that after this many scrolls. Re-verified boot to ok> on all three architectures (amd64/aarch64/riscv64) per repo acceptance policy. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
127 lines
4.6 KiB
C
127 lines
4.6 KiB
C
/*
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StarForth — Steady-State Virtual Machine Runtime
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Copyright (c) 2023–2025 Robert A. James
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All rights reserved.
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Licensed under the StarForth License, Version 1.0.
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*/
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/**
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* framebuffer.h — UEFI GOP framebuffer driver interface
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*
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* Pixel format: BGRX32 (PixelBlueGreenRedReserved8BitPerColor),
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* the dominant format for QEMU virt GOP. RGBX32 is also supported.
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*
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* Color values throughout this API are packed as 0x00RRGGBB.
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*/
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#ifndef STARKERNEL_FRAMEBUFFER_H
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#define STARKERNEL_FRAMEBUFFER_H
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#include <stdint.h>
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#include "uefi.h"
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/* Pixel format of the GOP framebuffer */
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typedef enum {
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FB_PIXEL_BGRX32 = 0, /* PixelBlueGreenRedReserved8BitPerColor (default) */
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FB_PIXEL_RGBX32 = 1, /* PixelRedGreenBlueReserved8BitPerColor */
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} FbPixelFormat;
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/* Pack / unpack 24-bit 0x00RRGGBB color */
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#define FB_RGB(r, g, b) \
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(((uint32_t)(r) << 16) | ((uint32_t)(g) << 8) | (uint32_t)(b))
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#define FB_R(c) (((uint32_t)(c) >> 16) & 0xFFu)
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#define FB_G(c) (((uint32_t)(c) >> 8) & 0xFFu)
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#define FB_B(c) ( (uint32_t)(c) & 0xFFu)
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/* Standard ANSI 16-color palette (indices 0–15) */
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extern const uint32_t FB_ANSI_PALETTE[16] __attribute__((visibility("hidden")));
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/* -----------------------------------------------------------------------
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* Lifecycle
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* --------------------------------------------------------------------- */
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/**
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* Initialize the framebuffer from UEFI bootloader GOP data.
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* Must be called before any other fb_* function.
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* fmt: pixel layout reported by GOP (default FB_PIXEL_BGRX32).
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*/
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void fb_init(const FramebufferInfo *info, FbPixelFormat fmt);
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/** Returns 1 if the framebuffer has been successfully initialized. */
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int fb_is_available(void);
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/* -----------------------------------------------------------------------
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* Geometry queries
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* --------------------------------------------------------------------- */
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uint32_t fb_width(void);
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uint32_t fb_height(void);
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/** Effective character cell width/height in pixels (8/16 × scale factor). */
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uint32_t fb_cell_w(void);
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uint32_t fb_cell_h(void);
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/* -----------------------------------------------------------------------
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* Pixel-level primitives
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* --------------------------------------------------------------------- */
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/** Write a single pixel. Out-of-bounds writes are silently ignored. */
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void fb_put_pixel(uint32_t x, uint32_t y, uint32_t rgb);
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/** Fill a rectangle with a solid color. */
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void fb_fill_rect(uint32_t x, uint32_t y, uint32_t w, uint32_t h,
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uint32_t rgb);
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/* -----------------------------------------------------------------------
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* Glyph rendering (8 × 16 font cells)
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* --------------------------------------------------------------------- */
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/**
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* Draw one 8×16 character glyph at pixel position (px, py).
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* fg / bg are packed 0x00RRGGBB colors.
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*/
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void fb_draw_glyph(uint32_t px, uint32_t py, uint8_t ch,
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uint32_t fg, uint32_t bg);
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/* -----------------------------------------------------------------------
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* Boot diagnostic
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* --------------------------------------------------------------------- */
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/**
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* One-time boot diagnostic (FABRIC.md item 4.3.1): fills each raster corner
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* with a distinct solid color so a screendump reveals orientation. Not part
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* of the Console drawing fabric -- diagnostic-only.
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*/
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void fb_draw_orientation_test(void);
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/* -----------------------------------------------------------------------
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* Scrolling
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* --------------------------------------------------------------------- */
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/**
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* Scroll the whole framebuffer up by `pixel_rows` pixel rows. The vacated
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* rows at the bottom are filled with bg. Takes an explicit pixel-row count
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* (not a hardcoded 8x16-cell assumption) so callers with a non-8x16 cell
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* height (e.g. TTF mode, 24px) pass their own cell height directly --
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* same convention fb_scroll_rect() below already uses, for the same reason
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* (a caller-computed char_rows * fixed-16px assumption drifts out of sync
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* with the text model's own row height in TTF mode, and that drift
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* compounds with every scroll).
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*/
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void fb_scroll_rows(uint32_t pixel_rows, uint32_t bg);
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/**
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* Scroll a sub-rectangle of the framebuffer up by `pixel_rows` pixel rows
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* (FABRIC.md item 4.4t: box-confined REPL scrolling). Unlike fb_scroll_rows()
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* (whole-framebuffer), this is bounded to
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* [x, x+w) x [y, y+h). Both take an explicit pixel-row count so callers with
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* a non-8x16 cell height (e.g. TTF mode) pass their own cell height directly.
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* Pixels outside the rect are untouched. The vacated rows at the bottom of
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* the rect are filled with bg.
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*/
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void fb_scroll_rect(uint32_t x, uint32_t y, uint32_t w, uint32_t h,
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uint32_t pixel_rows, uint32_t bg);
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#endif /* STARKERNEL_FRAMEBUFFER_H */
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