stmhal: Add stdin/stdout/stderr objects.

Available via sys.std{in,out,err}.  Basic reading and writing supported.
Even sys.stdin.readline!

stmhal/mpconfigport.h

@@ -19,6 +19,7 @@
 */
 #define MICROPY_ENABLE_LFN          (1)
 #define MICROPY_LFN_CODE_PAGE       (437) /* 1=SFN/ANSI 437=LFN/U.S.(OEM) */
+#define MICROPY_MOD_SYS_STDFILES    (1)
 
 // extra built in names to add to the global namespace
 extern const struct _mp_obj_fun_native_t mp_builtin_help_obj;

stmhal/pybstdio.c

+#include <stdio.h>
+
 #include <stm32f4xx_hal.h>
 
 #include "misc.h"
@@ -5,6 +7,7 @@
 #include "qstr.h"
 #include "misc.h"
 #include "obj.h"
+#include "stream.h"
 #include "pybstdio.h"
 #include "storage.h"
 #include "usb.h"
@@ -46,9 +49,97 @@ int stdin_rx_chr(void) {
         } else if (pyb_usart_global_debug != PYB_USART_NONE && usart_rx_any(pyb_usart_global_debug)) {
             return usart_rx_char(pyb_usart_global_debug);
         }
-        HAL_Delay(1);
+        __WFI();
         if (storage_needs_flush()) {
             storage_flush();
         }
     }
 }
+
+
+/******************************************************************************/
+// Micro Python bindings
+
+#define STDIO_FD_IN  (0)
+#define STDIO_FD_OUT (1)
+#define STDIO_FD_ERR (2)
+
+typedef struct _pyb_stdio_obj_t {
+    mp_obj_base_t base;
+    int fd;
+} pyb_stdio_obj_t;
+
+void stdio_obj_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t self_in, mp_print_kind_t kind) {
+    pyb_stdio_obj_t *self = self_in;
+    printf("<io.FileIO %d>", self->fd);
+}
+
+STATIC machine_int_t stdio_read(mp_obj_t self_in, void *buf, machine_uint_t size, int *errcode) {
+    pyb_stdio_obj_t *self = self_in;
+    if (self->fd == STDIO_FD_IN) {
+        for (uint i = 0; i < size; i++) {
+            int c = stdin_rx_chr();
+            if (c == '\r') {
+                c = '\n';
+            }
+            ((byte*)buf)[i] = c;
+        }
+        *errcode = 0;
+        return size;
+    } else {
+        *errcode = 1;
+        return 0;
+    }
+}
+
+STATIC machine_int_t stdio_write(mp_obj_t self_in, const void *buf, machine_uint_t size, int *errcode) {
+    pyb_stdio_obj_t *self = self_in;
+    if (self->fd == STDIO_FD_OUT || self->fd == STDIO_FD_ERR) {
+        stdout_tx_strn(buf, size);
+        *errcode = 0;
+        return size;
+    } else {
+        *errcode = 1;
+        return 0;
+    }
+}
+
+mp_obj_t stdio_obj___exit__(uint n_args, const mp_obj_t *args) {
+    return mp_const_none;
+}
+static MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(stdio_obj___exit___obj, 4, 4, stdio_obj___exit__);
+
+// TODO gc hook to close the file if not already closed
+
+STATIC const mp_map_elem_t stdio_locals_dict_table[] = {
+    { MP_OBJ_NEW_QSTR(MP_QSTR_read), (mp_obj_t)&mp_stream_read_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_readall), (mp_obj_t)&mp_stream_readall_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_readline), (mp_obj_t)&mp_stream_unbuffered_readline_obj},
+    { MP_OBJ_NEW_QSTR(MP_QSTR_write), (mp_obj_t)&mp_stream_write_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_close), (mp_obj_t)&mp_identity_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR___del__), (mp_obj_t)&mp_identity_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR___enter__), (mp_obj_t)&mp_identity_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR___exit__), (mp_obj_t)&stdio_obj___exit___obj },
+};
+
+STATIC MP_DEFINE_CONST_DICT(stdio_locals_dict, stdio_locals_dict_table);
+
+STATIC const mp_stream_p_t stdio_obj_stream_p = {
+    .read = stdio_read,
+    .write = stdio_write,
+};
+
+STATIC const mp_obj_type_t stdio_obj_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_FileIO,
+    // TODO .make_new?
+    .print = stdio_obj_print,
+    .getiter = mp_identity,
+    .iternext = mp_stream_unbuffered_iter,
+    .stream_p = &stdio_obj_stream_p,
+    .locals_dict = (mp_obj_t)&stdio_locals_dict,
+};
+
+const pyb_stdio_obj_t mp_sys_stdin_obj = {{&stdio_obj_type}, .fd = STDIO_FD_IN};
+const pyb_stdio_obj_t mp_sys_stdout_obj = {{&stdio_obj_type}, .fd = STDIO_FD_OUT};
+const pyb_stdio_obj_t mp_sys_stderr_obj = {{&stdio_obj_type}, .fd = STDIO_FD_ERR};