chore: import upstream snapshot with attribution

internal/cbm/zstd_store.c

@@ -0,0 +1,36 @@
+// zstd_store.c — Thin C wrappers around Zstandard.
+
+#include "vendored/zstd/zstd.h"
+
+#include "zstd_store.h"
+
+#include <stddef.h>
+#include <stdint.h>
+
+int cbm_zstd_compress(const char *src, int srcLen, char *dst, int dstCap, int level) {
+    size_t rc = ZSTD_compress(dst, (size_t)dstCap, src, (size_t)srcLen, level);
+    if (ZSTD_isError(rc)) {
+        return 0;
+    }
+    return (int)rc;
+}
+
+int64_t cbm_zstd_decompress(const char *src, size_t srcLen, char *dst, size_t dstCap) {
+    size_t rc = ZSTD_decompress(dst, dstCap, src, srcLen);
+    if (ZSTD_isError(rc)) {
+        return 0;
+    }
+    return (int64_t)rc;
+}
+
+size_t cbm_zstd_frame_content_size(const char *src, size_t srcLen) {
+    unsigned long long n = ZSTD_getFrameContentSize(src, srcLen);
+    if (n == ZSTD_CONTENTSIZE_UNKNOWN || n == ZSTD_CONTENTSIZE_ERROR) {
+        return 0;
+    }
+    return (size_t)n;
+}
+
+size_t cbm_zstd_compress_bound(int inputSize) {
+    return ZSTD_compressBound((size_t)inputSize);
+}