+"git-diff-stages [-p] [-r] [-z] [-R] [-B] [-M] [-C] [--find-copies-harder] [-O<orderfile>] [-S<string>] [--pickaxe-all] <stage1> <stage2> [<path>...]";
+
+static void diff_stages(int stage1, int stage2)
+{
+ int i = 0;
+ while (i < active_nr) {
+ struct cache_entry *ce, *stages[4] = { NULL, };
+ struct cache_entry *one, *two;
+ const char *name;
+ int len;
+ ce = active_cache[i];
+ len = ce_namelen(ce);
+ name = ce->name;
+ for (;;) {
+ int stage = ce_stage(ce);
+ stages[stage] = ce;
+ if (active_nr <= ++i)
+ break;
+ ce = active_cache[i];
+ if (ce_namelen(ce) != len ||
+ memcmp(name, ce->name, len))
+ break;
+ }
+ one = stages[stage1];
+ two = stages[stage2];
+ if (!one && !two)
+ continue;
+ if (!one)
+ diff_addremove('+', ntohl(two->ce_mode),
+ two->sha1, name, NULL);
+ else if (!two)
+ diff_addremove('-', ntohl(one->ce_mode),
+ one->sha1, name, NULL);
+ else if (memcmp(one->sha1, two->sha1, 20) ||
+ (one->ce_mode != two->ce_mode) ||
+ find_copies_harder)
+ diff_change(ntohl(one->ce_mode), ntohl(two->ce_mode),
+ one->sha1, two->sha1, name, NULL);
+ }
+}