160 lines
6.5 KiB
C
160 lines
6.5 KiB
C
/*
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* gfx.h — Sprinter graphics primitives.
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*
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* Two main modes:
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* GFX_MODE_320x256x256 (0x81) — one byte per pixel, palette of 256
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* entries. API functions suffixed _256.
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* GFX_MODE_640x256x16 (0x82) — 4 bits per pixel, palette of 16.
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* API functions suffixed _16.
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*
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* Common API (no suffix) covers things that are mode-agnostic:
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* gfx_init / gfx_done
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* gfx_set_visible_page / gfx_set_draw_page / gfx_set_bank
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* gfx_wait_vsync
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* gfx_pal_load / gfx_pal_set
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* gfx_load_default_font / gfx_set_font
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*
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* Addressing reminder:
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* pixel (x, y) lives at CPU 0xC000 + (x or x/2) with Port_Y (0x89) = y;
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* the gfx code maps a 16 KB VRAM page into W3 around every write.
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* For double-buffering, page 1 starts 320 bytes later (0xC140).
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*
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* Palette: BIOS $A4 (RST 8); 4 bytes per entry — B, G, R, pad.
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*/
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#ifndef GFX_H
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#define GFX_H
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#include <stdint.h>
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/* ESTEX SETVMOD codes — same values as the SETVMOD `A` register. */
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#define GFX_MODE_TEXT_40x32 0x02
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#define GFX_MODE_TEXT_80x32 0x03
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#define GFX_MODE_320x256x256 0x81
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#define GFX_MODE_640x256x16 0x82
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/* Pixel dimensions of mode 0x81 (320×256, 256 colours). */
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#define GFX_WIDTH 320
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#define GFX_HEIGHT 256
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/* Pixel dimensions of mode 0x82 (640×256, 16 colours). Each byte at
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* 0xC000+x_byte holds two pixels: high nibble = LEFT (even-x), low
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* nibble = RIGHT (odd-x) — see memory/sprinter_graphics.md. */
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#define GFX_WIDTH_16 640
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#define GFX_HEIGHT_16 256
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#define GFX_COLORS_16 16
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/* ---- Setup / teardown -------------------------------------------- *
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*
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* Switch to `mode`, returning the previous mode for restore. `page`
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* (0 or 1) selects the initial graphics screen — both the visible and
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* the draw page are set to it, and the W3 bank is reset to 0x50 (the
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* canonical visible video page). Programs that don't double-buffer
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* just pass 0. */
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uint8_t gfx_init(uint8_t mode, uint8_t page);
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/* Restore a previously-saved video mode. */
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void gfx_done(uint8_t mode);
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/* ---- Page selection (double-buffering) and bank control ---------- *
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*
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* The Sprinter hardware holds two graphics screens. The VISIBLE page
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* is what's shown on screen; the DRAW page is where the gfx_* writes
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* land. Render the next frame into the hidden page and flip when ready.
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*
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* "Bank" is the W3 page byte (0x50..0x5F) — bits 2,3 select
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* normal/temp/transparent display modes. All gfx_* primitives map
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* THIS bank into W3 before touching 0xC000+. Default is 0x50. */
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void gfx_set_visible_page(uint8_t page); /* 0 or 1 */
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uint8_t gfx_get_visible_page(void);
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void gfx_set_draw_page(uint8_t page); /* 0 or 1 */
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uint8_t gfx_get_draw_page(void);
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void gfx_set_bank(uint8_t bank); /* 0x50..0x5F */
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uint8_t gfx_get_bank(void);
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/* Block until the next frame interrupt (50 Hz on Sprinter). Uses
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* `EI; HALT` — the Z80 sleeps until the next IM2 tick that DSS programs
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* for keyboard / cursor handling. Typical use:
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*
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* gfx_set_draw_page(hidden);
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* draw_frame(...);
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* gfx_wait_vsync(); // wait for vretrace
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* gfx_set_visible_page(hidden); // tear-free flip
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*/
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void gfx_wait_vsync(void);
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/* ---- 320×256×256 (mode 0x81) drawing API -------------------------- *
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* Colour args are palette indices 0..255. */
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void gfx_clear256 (uint8_t color);
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void gfx_putpixel256 (int x, int y, uint8_t color);
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void gfx_hline256 (int x, int y, int len, uint8_t color);
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void gfx_vline256 (int x, int y, int len, uint8_t color);
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void gfx_line256 (int x0, int y0, int x1, int y1, uint8_t color);
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void gfx_rect256 (int x, int y, int w, int h, uint8_t color);
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void gfx_fill_rect256(int x, int y, int w, int h, uint8_t color);
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/* ---- 640×256×16 (mode 0x82) drawing API --------------------------- *
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* Colour args are palette indices 0..15. The accelerator works
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* byte-wise so vline16 falls back to per-row RMW (a byte spans two
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* horizontal pixels). */
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void gfx_clear16 (uint8_t color);
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void gfx_putpixel16 (int x, int y, uint8_t color);
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void gfx_hline16 (int x, int y, int len, uint8_t color);
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void gfx_vline16 (int x, int y, int len, uint8_t color);
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void gfx_line16 (int x0, int y0, int x1, int y1, uint8_t color);
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void gfx_rect16 (int x, int y, int w, int h, uint8_t color);
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void gfx_fill_rect16(int x, int y, int w, int h, uint8_t color);
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/* ---- Bitmap-font text -------------------------------------------- *
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* Font is 256 glyphs × 8 rows × 1 byte (ZX-Spectrum format), 2 KB.
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* On first use the default system font is fetched via BIOS WIN_GET_ZG
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* (fn 0xB8). gfx_set_font() lets you swap in a custom font (the
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* pointer is held — keep the storage alive). */
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void gfx_load_default_font(void);
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void gfx_set_font(const uint8_t *font);
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/* 320×256×256 text: one byte per pixel; advances x by 8 per char. */
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void gfx_putchar256(int x, int y, char c, uint8_t fg, uint8_t bg);
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void gfx_text256 (int x, int y, const char *s, uint8_t fg, uint8_t bg);
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/* 640×256×16 text: 4 bits per pixel; x must be EVEN (byte-aligned). */
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void gfx_putchar16 (int x, int y, char c, uint8_t fg, uint8_t bg);
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void gfx_text16 (int x, int y, const char *s, uint8_t fg, uint8_t bg);
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/* ---- Palette ----------------------------------------------------- *
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* Each graphics page has its own palette page (page 0 → palette 0,
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* page 1 → palette 1). For seamless double-buffering, load the same
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* palette into both. */
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/* Load a contiguous block of palette entries.
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* pal_num: 0..3 (graphics palettes)
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* start: first colour slot (0..255)
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* count: number of slots (0 → 256)
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* data: pointer to count entries, each formatted (B, G, R, 0). */
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void gfx_pal_load(uint8_t pal_num, uint8_t start, uint8_t count,
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const uint8_t *data);
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/* Convenience: set one palette entry from RGB. Internally builds the
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* BGR+pad triple and calls gfx_pal_load(pal_num, idx, 1, ...). */
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void gfx_pal_set (uint8_t pal_num, uint8_t idx,
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uint8_t r, uint8_t g, uint8_t b);
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/* Read a contiguous block of entries back from a graphics palette. */
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void gfx_pal_get (uint8_t pal_num, uint8_t start, uint8_t count,
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uint8_t *data);
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/* Read one entry into R, G, B pointers (any may be NULL). */
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void gfx_pal_get_color(uint8_t pal_num, uint8_t idx,
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uint8_t *r, uint8_t *g, uint8_t *b);
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/* Restore the system default graphics palette (BIOS $A6, type=1). */
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void gfx_pal_reset(void);
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#endif
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