add save module: checked chunk files

1 files changed, 99 insertions, 0 deletions

diff --git a/kon/konsave.h b/kon/konsave.h
new file mode 100644
index 0000000..45e45c1
--- /dev/null
+++ b/kon/konsave.h
@@ -0,0 +1,99 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * konsave.h
+ *
+ * Copyright (c) 2026 KonAki
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef KONSAVE_H
+#define KONSAVE_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+/*** definition ***/
+
+/* a save is a list of tagged chunks, so each part of a game writes and reads its own and a menu can read just
+the little META chunk of every slot. whole thing is checked with a crc, a damaged or cut short file is refused. numbers
+are little endian whatever the machine. it all happens in a buffer you own, the file functions are at the end */
+
+typedef struct kon_saveWriter {
+	uint8_t *buf;
+	size_t cap, len, chunk;
+	int error, open;
+} kon_saveWriter_t;
+
+typedef struct kon_saveReader {
+	const uint8_t *buf;
+	size_t len;
+	uint32_t version; /* the number you gave kon_saveBegin, to change old saves into new ones */
+} kon_saveReader_t;
+
+typedef struct kon_saveCursor {
+	const uint8_t *p, *end;
+	int error; /* reading past the end gives 0s and sets this */
+} kon_saveCursor_t;
+
+/*** writing ***/
+
+void kon_saveBegin(kon_saveWriter_t *w, void *buf, size_t cap, uint32_t version);
+void kon_saveChunk(kon_saveWriter_t *w, const char *tag); /* four characters, ends the chunk before it */
+void kon_savePutU8(kon_saveWriter_t *w, unsigned v);
+void kon_savePutU16(kon_saveWriter_t *w, unsigned v);
+void kon_savePutU32(kon_saveWriter_t *w, uint32_t v);
+void kon_savePutI32(kon_saveWriter_t *w, int32_t v);
+void kon_savePutF32(kon_saveWriter_t *w, float v);
+void kon_savePutBytes(kon_saveWriter_t *w, const void *data, size_t n);
+void kon_savePutString(kon_saveWriter_t *w, const char *s); /* up to 65535 bytes */
+void kon_savePutSwitches(kon_saveWriter_t *w, const uint8_t *switches, int count);
+void kon_savePutVars(kon_saveWriter_t *w, const int32_t *vars, int count);
+
+/* how many bytes the save is, or 0 if it did not fit in the buffer */
+size_t kon_saveEnd(kon_saveWriter_t *w);
+
+/*** reading ***/
+
+/* 0 if it is not a save, is damaged or is cut short */
+int kon_saveOpen(kon_saveReader_t *r, const void *buf, size_t len);
+int kon_saveFind(const kon_saveReader_t *r, const char *tag, kon_saveCursor_t *c);
+
+unsigned kon_saveGetU8(kon_saveCursor_t *c);
+unsigned kon_saveGetU16(kon_saveCursor_t *c);
+uint32_t kon_saveGetU32(kon_saveCursor_t *c);
+int32_t kon_saveGetI32(kon_saveCursor_t *c);
+float kon_saveGetF32(kon_saveCursor_t *c);
+void kon_saveGetBytes(kon_saveCursor_t *c, void *out, size_t n);
+void kon_saveGetString(kon_saveCursor_t *c, char *out, size_t size); /* always ends with a 0, cut if it does not fit */
+
+/* into what you have, if the save had more they are dropped and if fewer the rest are 0. return how many the save had */
+int kon_saveGetSwitches(kon_saveCursor_t *c, uint8_t *switches, int count);
+int kon_saveGetVars(kon_saveCursor_t *c, int32_t *vars, int count);
+
+/*** files ***/
+
+/* written beside the real name first and then moved over it, so a crash leaves the old save. on Windows the old one
+is removed just before the move. 1 if it worked */
+int kon_saveWriteFile(const char *path, const void *buf, size_t len);
+
+/* how many bytes were read, or -1 if it could not be opened or does not fit in cap */
+long kon_saveReadFile(const char *path, void *buf, size_t cap);
+
+#endif /* KONSAVE_H */