75 lines
3.1 KiB
C
75 lines
3.1 KiB
C
// Surface type and allocation.
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//
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// All surfaces are 320x200 16-color images. In-memory storage is
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// target-native: chunky 4bpp packed (two pixels per byte, high nibble
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// is the left pixel) on IIgs and DOS; native planar (4 separate
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// bitplanes on Amiga, word-interleaved planes on Atari ST) on the
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// 68k ports. Public API entry points speak in color indices (0..15)
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// regardless, so game code does not see the storage format.
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//
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// Each surface carries its own 200-entry SCB (scanline control byte)
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// table and a 16-by-16 $0RGB palette set. See docs/DESIGN.md section 6.
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#ifndef JOEYLIB_SURFACE_H
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#define JOEYLIB_SURFACE_H
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#include "platform.h"
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#include "types.h"
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// ----- Fixed surface dimensions (library contract) -----
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#define SURFACE_WIDTH 320
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#define SURFACE_HEIGHT 200
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#define SURFACE_BYTES_PER_ROW 160
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#define SURFACE_PIXELS_SIZE (SURFACE_BYTES_PER_ROW * SURFACE_HEIGHT)
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#define SURFACE_PALETTE_COUNT 16
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#define SURFACE_COLORS_PER_PALETTE 16
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#define SURFACE_PALETTE_ENTRIES (SURFACE_PALETTE_COUNT * SURFACE_COLORS_PER_PALETTE)
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// ----- Opaque public type -----
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typedef struct SurfaceT SurfaceT;
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// Allocate a new offscreen surface. Returns NULL on failure (joeyLastError
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// describes the reason).
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SurfaceT *surfaceCreate(void);
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// Release an offscreen surface previously returned by surfaceCreate.
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// Passing NULL is a no-op. Passing the stage is a no-op.
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void surfaceDestroy(SurfaceT *s);
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// The library-owned stage: the back-buffer surface that stagePresent
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// flips to the display. Always valid between joeyInit and joeyShutdown.
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// On IIgs the stage's pixel buffer is pinned to bank $01 SHR space with
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// shadow inhibited so writes are full-speed (2.8 MHz) and isolated from
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// the displayed framebuffer until the next stagePresent.
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SurfaceT *stageGet(void);
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// Copy pixels, SCBs, and palettes from src into dst. Both must be valid
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// surfaces.
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void surfaceCopy(SurfaceT *dst, const SurfaceT *src);
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// Persist a surface to disk in target-native form: 32000 bytes of
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// pixels followed by 200 bytes of SCB followed by 512 bytes of $0RGB
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// palette table (16 palettes x 16 colors, native uint16_t). Returns
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// false if the file can't be opened or the write fails. The same
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// platform that wrote the file must read it -- no endianness
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// conversion is performed.
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bool surfaceSaveFile(const SurfaceT *src, const char *path);
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// Read a surface from disk, overwriting dst. Returns false if the
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// file is missing, the wrong size, or the read fails. dst keeps its
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// identity (no reallocation).
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bool surfaceLoadFile(SurfaceT *dst, const char *path);
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// FNV-1a 32-bit hash of the surface's logical pixel content (color
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// indices in row-major order, 0..15 per pixel). Same logical pixels
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// produce the same hash on every port regardless of internal storage
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// format -- so a hash captured on IIgs (chunky) compares directly
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// against the same op's output on Amiga (planar) once the planar
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// rewrite is done. Used by the UBER validation harness to
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// pixel-compare ports against an IIgs golden reference.
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uint32_t surfaceHash(const SurfaceT *s);
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#endif
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