extmod/uos_dupterm: Update uos.dupterm() and helper funcs to have index.

The uos.dupterm() signature and behaviour is updated to reflect the latest
enhancements in the docs.  It has minor backwards incompatibility in that
it no longer accepts zero arguments.

The dupterm_rx helper function is moved from esp8266 to extmod and
generalised to support multiple dupterm slots.

A port can specify multiple slots by defining the MICROPY_PY_OS_DUPTERM
config macro to an integer, being the number of slots it wants to have;
0 means to disable the dupterm feature altogether.

The unix and esp8266 ports are updated to work with the new interface and
are otherwise unchanged with respect to functionality.

1 files changed, 9 insertions, 8 deletions

diff --git a/ports/unix/unix_mphal.c b/ports/unix/unix_mphal.c
index 2b273d834..f27c62fd1 100644
--- a/ports/unix/unix_mphal.c
+++ b/ports/unix/unix_mphal.c
@@ -108,11 +108,11 @@ void mp_hal_stdio_mode_orig(void) {
 #endif
 
 #if MICROPY_PY_OS_DUPTERM
-static int call_dupterm_read(void) {
+static int call_dupterm_read(size_t idx) {
     nlr_buf_t nlr;
     if (nlr_push(&nlr) == 0) {
         mp_obj_t read_m[3];
-        mp_load_method(MP_STATE_PORT(term_obj), MP_QSTR_read, read_m);
+        mp_load_method(MP_STATE_VM(dupterm_objs[idx]), MP_QSTR_read, read_m);
         read_m[2] = MP_OBJ_NEW_SMALL_INT(1);
         mp_obj_t res = mp_call_method_n_kw(1, 0, read_m);
         if (res == mp_const_none) {
@@ -122,18 +122,18 @@ static int call_dupterm_read(void) {
         mp_get_buffer_raise(res, &bufinfo, MP_BUFFER_READ);
         if (bufinfo.len == 0) {
             mp_printf(&mp_plat_print, "dupterm: EOF received, deactivating\n");
-            MP_STATE_PORT(term_obj) = NULL;
+            MP_STATE_VM(dupterm_objs[idx]) = MP_OBJ_NULL;
             return -1;
         }
         nlr_pop();
         return *(byte*)bufinfo.buf;
     } else {
         // Temporarily disable dupterm to avoid infinite recursion
-        mp_obj_t save_term = MP_STATE_PORT(term_obj);
-        MP_STATE_PORT(term_obj) = NULL;
+        mp_obj_t save_term = MP_STATE_VM(dupterm_objs[idx]);
+        MP_STATE_VM(dupterm_objs[idx]) = NULL;
         mp_printf(&mp_plat_print, "dupterm: ");
         mp_obj_print_exception(&mp_plat_print, nlr.ret_val);
-        MP_STATE_PORT(term_obj) = save_term;
+        MP_STATE_VM(dupterm_objs[idx]) = save_term;
     }
 
     return -1;
@@ -143,10 +143,11 @@ static int call_dupterm_read(void) {
 int mp_hal_stdin_rx_chr(void) {
     unsigned char c;
 #if MICROPY_PY_OS_DUPTERM
-    if (MP_STATE_PORT(term_obj) != MP_OBJ_NULL) {
+    // TODO only support dupterm one slot at the moment
+    if (MP_STATE_VM(dupterm_objs[0]) != MP_OBJ_NULL) {
         int c;
         do {
-             c = call_dupterm_read();
+             c = call_dupterm_read(0);
         } while (c == -2);
         if (c == -1) {
             goto main_term;