84 lines
3.6 KiB
C
84 lines
3.6 KiB
C
// Surface type and allocation.
|
|
//
|
|
// All surfaces are 320x200 16-color images. In-memory storage is
|
|
// target-native: chunky 4bpp packed (two pixels per byte, high nibble
|
|
// is the left pixel) on IIgs and DOS; native planar (4 separate
|
|
// bitplanes on Amiga, word-interleaved planes on Atari ST) on the
|
|
// 68k ports. Public API entry points speak in color indices (0..15)
|
|
// regardless, so game code does not see the storage format.
|
|
//
|
|
// Each surface carries its own 200-entry SCB (scanline control byte)
|
|
// table and a 16-by-16 $0RGB palette set. See docs/DESIGN.md section 6.
|
|
|
|
#ifndef JOEYLIB_SURFACE_H
|
|
#define JOEYLIB_SURFACE_H
|
|
|
|
#include "platform.h"
|
|
#include "types.h"
|
|
|
|
// ----- Fixed surface dimensions (library contract) -----
|
|
|
|
#define SURFACE_WIDTH 320
|
|
#define SURFACE_HEIGHT 200
|
|
#define SURFACE_BYTES_PER_ROW 160
|
|
#define SURFACE_PIXELS_SIZE (SURFACE_BYTES_PER_ROW * SURFACE_HEIGHT)
|
|
|
|
#define SURFACE_PALETTE_COUNT 16
|
|
#define SURFACE_COLORS_PER_PALETTE 16
|
|
#define SURFACE_PALETTE_ENTRIES (SURFACE_PALETTE_COUNT * SURFACE_COLORS_PER_PALETTE)
|
|
|
|
// ----- Opaque public type -----
|
|
|
|
typedef struct jlSurfaceT jlSurfaceT;
|
|
|
|
// Allocate a new offscreen surface. Returns NULL on failure (jlLastError
|
|
// describes the reason).
|
|
jlSurfaceT *jlSurfaceCreate(void);
|
|
|
|
// Release an offscreen surface previously returned by jlSurfaceCreate.
|
|
// Passing NULL is a no-op. Passing the stage is a no-op.
|
|
void jlSurfaceDestroy(jlSurfaceT *s);
|
|
|
|
// The library-owned stage: the back-buffer surface that jlStagePresent
|
|
// flips to the display. Always valid between jlInit and jlShutdown.
|
|
// On IIgs the stage's pixel buffer is pinned to bank $01 SHR space with
|
|
// shadow inhibited so writes are full-speed (2.8 MHz) and isolated from
|
|
// the displayed framebuffer until the next jlStagePresent.
|
|
jlSurfaceT *jlStageGet(void);
|
|
|
|
// Copy pixels, SCBs, and palettes from src into dst. Both must be valid
|
|
// surfaces.
|
|
void jlSurfaceCopy(jlSurfaceT *dst, const jlSurfaceT *src);
|
|
|
|
// Persist a surface to disk in target-native form: 32000 bytes of
|
|
// pixels followed by 200 bytes of SCB followed by 512 bytes of $0RGB
|
|
// palette table (16 palettes x 16 colors, native uint16_t). Returns
|
|
// false if the file can't be opened or the write fails. The same
|
|
// platform that wrote the file must read it -- no endianness
|
|
// conversion is performed.
|
|
bool jlSurfaceSaveFile(const jlSurfaceT *src, const char *path);
|
|
|
|
// Read a surface from disk, overwriting dst. Returns false if the
|
|
// file is missing, the wrong size, or the read fails. dst keeps its
|
|
// identity (no reallocation).
|
|
bool jlSurfaceLoadFile(jlSurfaceT *dst, const char *path);
|
|
|
|
// 32-bit content hash of the surface. NOT FNV-1a: a two-stream 16-bit
|
|
// multiplicative hash -- per input byte b, lo = lo * 31 + b and
|
|
// hi = hi * 251 + b (mod 2^16), seeded lo = 0xACE1 / hi = 0x1357, and
|
|
// combined as (hi << 16) | lo. The hashed domain, in order:
|
|
// 1. the packed chunky pixel byte stream (32000 bytes, two 4-bit
|
|
// pixels per byte, high nibble = left pixel, row-major),
|
|
// 2. the 200 SCB bytes,
|
|
// 3. the 256 palette uint16 entries, each folded high byte then
|
|
// low byte.
|
|
// SURFACE_HASH_MIX_BYTE in src/core/surfaceInternal.h is the single
|
|
// source of truth for the per-byte mix; a port override (the planar
|
|
// Amiga/ST readers) must reuse it byte-for-byte and feed the identical
|
|
// byte sequence, so the same logical pixels produce the same hash on
|
|
// every port regardless of internal storage format. Used by the UBER
|
|
// validation harness to pixel-compare ports against an IIgs golden
|
|
// reference.
|
|
uint32_t jlSurfaceHash(const jlSurfaceT *s);
|
|
|
|
#endif
|