C API¶

The shared library exposes a C ABI for integration with any language that supports foreign function calls.

Function signatures¶

Function	Signature	Description
`msdrg_context_init`	`void(const char data_dir)`	Create a grouper context
`msdrg_group_json`	`const char(void ctx, const char* json)`	Group a claim (JSON in → JSON out)
`msdrg_context_free`	`void(void* ctx)`	Free a grouper context
`mce_context_init`	`void(const char data_dir)`	Create an MCE context
`mce_edit_json`	`const char(void ctx, const char* json)`	Run MCE (JSON in → JSON out)
`mce_context_free`	`void(void* ctx)`	Free an MCE context
`msdrg_string_free`	`void(const char* str)`	Free a returned JSON string

MS-DRG Grouper¶

#include <stdio.h>

// Initialize context with path to binary data files
void* ctx = msdrg_context_init("/path/to/data/bin");
if (!ctx) {
    fprintf(stderr, "Failed to initialize grouper\n");
    return 1;
}

// Group a claim (JSON in, JSON out)
const char* result = msdrg_group_json(ctx, "{\"version\":431,\"age\":65,\"sex\":0,\"discharge_status\":1,\"pdx\":{\"code\":\"I5020\"},\"sdx\":[],\"procedures\":[]}");
printf("%s\n", result);

// Free the returned string, then the context
msdrg_string_free(result);
msdrg_context_free(ctx);

MCE Editor¶

// Initialize MCE context (same data directory)
void* mce = mce_context_init("/path/to/data/bin");
if (!mce) {
    fprintf(stderr, "Failed to initialize MCE\n");
    return 1;
}

// Edit a claim
const char* result = mce_edit_json(mce, "{\"discharge_date\":20250101,\"age\":65,\"sex\":0,\"discharge_status\":1,\"pdx\":{\"code\":\"I5020\"},\"sdx\":[],\"procedures\":[]}");
printf("%s\n", result);

// Free
msdrg_string_free(result);
mce_context_free(mce);

Error handling¶

msdrg_context_init / mce_context_init return NULL if the data directory is invalid or data files cannot be loaded.
msdrg_group_json / mce_edit_json return NULL if the input JSON is malformed or processing fails.
Always check for NULL before using the returned string.

Thread safety¶

Contexts are immutable after initialization and safe to share across threads. Each call to msdrg_group_json / mce_edit_json is independently thread-safe — no external locking is required.

Tip

Both contexts can coexist in the same process and share the same shared library. Initialize once, call from any thread.