py: Optimise call to mp_arg_check_num by compressing fun signature.

With 5 arguments to mp_arg_check_num(), some architectures need to pass
values on the stack.  So compressing n_args_min, n_args_max, takes_kw into
a single word and passing only 3 arguments makes the call more efficient,
because almost all calls to this function pass in constant values.  Code
size is also reduced by a decent amount:

   bare-arm:  -116
minimal x86:   -64
   unix x64:  -256
unix nanbox:  -112
      stm32:  -324
     cc3200:  -192
    esp8266:  -192
      esp32:  -144

1 files changed, 6 insertions, 1 deletions

diff --git a/py/argcheck.c b/py/argcheck.c
index d53bca73a..c018f3fe7 100644
--- a/py/argcheck.c
+++ b/py/argcheck.c
@@ -29,9 +29,14 @@
 
 #include "py/runtime.h"
 
-void mp_arg_check_num(size_t n_args, size_t n_kw, size_t n_args_min, size_t n_args_max, bool takes_kw) {
+void mp_arg_check_num_sig(size_t n_args, size_t n_kw, uint32_t sig) {
     // TODO maybe take the function name as an argument so we can print nicer error messages
 
+    // The reverse of MP_OBJ_FUN_MAKE_SIG
+    bool takes_kw = sig & 1;
+    size_t n_args_min = sig >> 17;
+    size_t n_args_max = (sig >> 1) & 0xffff;
+
     if (n_kw && !takes_kw) {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
             mp_arg_error_terse_mismatch();