layout.cpp

Go to the documentation of this file.

// CMSDK DataMessage wire-layout dump: the single source of truth for non-C++ codecs.
//
// Prints the byte layout of DataMessageHeader (offset + size of every field, as the C++
// compiler lays it out, including padding), the entry header, the content-type ids and the
// constants a codec needs, as JSON. kotlin/fixtures/layout.json is this program's output and
// the Kotlin codec's tests check their own offsets against it, so a change to the C++ struct
// fails the Kotlin build until the codec is updated.
//
// Build + run (from CMSDK/):  make -C kotlin/tools   (writes kotlin/fixtures/layout.json)
#include "DataMessage.h"
#include "ObjectIDs.h"
#include "PsyTime.h"
#include <cstddef>
#include <cstdio>
 
using namespace cmlabs;
 
#define F(name) printf("    \"%s\": { \"offset\": %u, \"size\": %u },\n", #name, \
    (unsigned)offsetof(DataMessageHeader, name), (unsigned)sizeof(((DataMessageHeader*)0)->name))
#define FL(name) printf("    \"%s\": { \"offset\": %u, \"size\": %u }\n", #name, \
    (unsigned)offsetof(DataMessageHeader, name), (unsigned)sizeof(((DataMessageHeader*)0)->name))
 
int main() {
    printf("{\n");
    printf("  \"format\": \"CMSDK DataMessage\",\n");
    printf("  \"version\": %u,\n", (unsigned)CURRENTDATAMESSAGEVERSION);
    printf("  \"byteOrder\": \"little-endian (native host order; x86/ARM)\",\n");
    printf("  \"headerSize\": %u,\n", (unsigned)sizeof(DataMessageHeader));
    printf("  \"entryHeaderSize\": %u,\n", (unsigned)sizeof(DataMessageEntryHeader));
    printf("  \"psyTypeLevels\": %u,\n", (unsigned)PSYTYPELEVELS);
    printf("  \"psyContextLevels\": %u,\n", (unsigned)PSYCONTEXTLEVELS);
    printf("  \"usecYear0To1970\": %lld,\n", (long long)USEC_YEAR_0_TO_1970);
    printf("  \"ids\": { \"DATAMESSAGEID\": %u, \"UNUSEDID\": %u, \"CONSTCHARID\": %u, \"TIMEID\": %u, "
        "\"CHARDATAID\": %u, \"INTID\": %u, \"DOUBLEID\": %u },\n",
        (unsigned)DATAMESSAGEID, (unsigned)UNUSEDID, (unsigned)CONSTCHARID, (unsigned)TIMEID,
        (unsigned)CHARDATAID, (unsigned)INTID, (unsigned)DOUBLEID);
    printf("  \"header\": {\n");
    F(size); F(cid); F(cver); F(cenc); F(memid); F(time); F(sendtime); F(recvtime);
    F(origin); F(destination); F(ttl); F(priority); F(policy); F(from); F(to); F(type);
    F(tag); F(status); F(reference); F(serial); F(contextchange); F(userSize); F(userCount);
    F(cyclecputime); F(cyclewalltime); F(chaincputime); F(chainwalltime); F(chaincount);
    FL(systemid);
    printf("  }\n}\n");
    return 0;
}