C FFI quickstart

cargo build --release -p dicom-map-ffi
# -> target/release/libdicom_map_ffi.{so,a,dylib}
# header: dicom-map-ffi/include/dicom_map.h

#include "dicom_map.h"
#include <stdio.h>

int main(void) {
    DmapHandle *h = dmap_open("tags.dmap");
    if (!h) {
        fprintf(stderr, "open failed\n");
        return 1;
    }

    DmapTag *t = dmap_lookup(h, 0x0008, 0x0005, NULL);
    if (t) {
        printf("%s %s\n", t->vr, t->keyword);
        dmap_free_tag(t);
    }

    DmapTag *p = dmap_lookup(h, 0x0021, 0x0008,
                             "Siemens: Thorax/Multix FD Lab Settings");
    if (p) {
        printf("%s %s\n", p->vr, p->name);
        dmap_free_tag(p);
    }

    dmap_close(h);
    return 0;
}

Build:

gcc -Wall -O2 \
    -I dicom-map-ffi/include \
    smoke.c \
    -L target/release -ldicom_map_ffi \
    -o smoke

LD_LIBRARY_PATH=target/release ./smoke

ABI guarantees

The FFI surface is extern "C" with C-stable layouts on the returned DmapTag struct. The handle is opaque. All pointers returned by dmap_lookup and dmap_last_error must be freed by the corresponding dmap_free_* function. See dicom_map.h for the authoritative declarations.