faster cython loop

selfdrive/boardd/boardd_api_impl.pyx

@@ -1,5 +1,6 @@
 # distutils: language = c++
 # cython: language_level=3
+from cython.operator cimport dereference as deref, preincrement as preinc
 from libcpp.vector cimport vector
 from libcpp.string cimport string
 from libcpp cimport bool
@@ -45,7 +46,11 @@ def can_capnp_to_list(strings, sendcan=False):
  cdef vector[CanData] data
  can_capnp_to_can_list_cpp(strings, data, sendcan)
  result = []
- for c in data:
- frames = [[f.address, 0, f.dat, f.src] for f in c.frames]
- result.append([c.nanos, frames])
+ cdef vector[CanData].iterator it = data.begin()
+ cdef CanData *d
+ while it != data.end():
+ d = &deref(it)
+ frames = [[f.address, 0, (<char *>&f.dat[0])[:f.dat.size()], f.src] for f in d.frames]
+ result.append([d.nanos, frames])
+ preinc(it)
  return result