comparison mercurial/cext/revlog.c @ 40703:d5b300ec2e89

sparse-revlog: add a `index_get_start` function in C

We are about to implement a native version of `slicechunktodensity`. For
clarity, we introduce the helper functions first. This new function provides
an efficient way to retrieve some of the information needed by
`slicechunktodensity`.

40702:4240a1da4188

	if (ps[0] > maxrev || ps[1] > maxrev) {
		PyErr_SetString(PyExc_ValueError, "parent out of range");
		return -1;
	}
	return 0;
}

/*
 * RevlogNG format (all in big endian, data may be inlined):
 *    6 bytes: offset

40703:d5b300ec2e89

	if (ps[0] > maxrev || ps[1] > maxrev) {
		PyErr_SetString(PyExc_ValueError, "parent out of range");
		return -1;
	}
	return 0;
}

static inline int64_t index_get_start(indexObject *self, Py_ssize_t rev)
{
	uint64_t offset;
	if (rev >= self->length) {
		PyObject *tuple;
		PyObject *pylong;
		PY_LONG_LONG tmp;
		tuple = PyList_GET_ITEM(self->added, rev - self->length);
		pylong = PyTuple_GET_ITEM(tuple, 0);
		tmp = PyLong_AsLongLong(pylong);
		if (tmp == -1 && PyErr_Occurred()) {
			return -1;
		}
		if (tmp < 0) {
			PyErr_Format(PyExc_OverflowError,
			             "revlog entry size out of bound (%lld)",
			             (long long)tmp);
			return -1;
		}
		offset = (uint64_t)tmp;
	} else {
		const char *data = index_deref(self, rev);
		offset = getbe32(data + 4);
		if (rev == 0) {
			/* mask out version number for the first entry */
			offset &= 0xFFFF;
		} else {
			uint32_t offset_high = getbe32(data);
			offset |= ((uint64_t)offset_high) << 32;
		}
	}
	return (int64_t)(offset >> 16);
}

/*
 * RevlogNG format (all in big endian, data may be inlined):
 *    6 bytes: offset