ports/*: Various changes to implement multiple-output logic.

This is an attempt to implement the following logic:

"mp_hal_stdout_tx_strn() should attempt to write len bytes to all of the
possible destinations for that data, and return the minimum successful
write length"

Implementing this is complicated by these facts:
- multiple outputs may be enabled/disabled at compiled time
- multiple outputs may be enabled/disabled at runtime
- mp_os_dupterm_tx_strn() is one such output, optionally containing
  multiple additional outputs
- each of these outputs may or may not be able to report success
- each of these outputs may or may not be able to report partial writes

The result is that there is no single approach that can be followed for
various ports, so each instance of mp_hal_stdout_tx_strn() has its own
logic.

Additionally, cases where "mp_uint_t ret = len;" with len unchanged in the
function, are changed to simply return len. Note that some instances of
mp_hal_stdout_tx_strn() modify len while writing, others don't.

Signed-off-by: Maarten van der Schrieck <maarten@thingsconnected.nl>

Author: mvds00

ports/cc3200/hal/cc3200_hal.c

@@ -142,7 +142,6 @@ void mp_hal_delay_ms(mp_uint_t delay) {
 }
 
 mp_uint_t mp_hal_stdout_tx_strn(const char *str, size_t len) {
-    mp_uint_t ret = len;
     if (MP_STATE_PORT(os_term_dup_obj)) {
         if (mp_obj_is_type(MP_STATE_PORT(os_term_dup_obj)->stream_o, &pyb_uart_type)) {
             uart_tx_strn(MP_STATE_PORT(os_term_dup_obj)->stream_o, str, len);
@@ -153,7 +152,7 @@ mp_uint_t mp_hal_stdout_tx_strn(const char *str, size_t len) {
     }
     // and also to telnet
     telnet_tx_strn(str, len);
-    return ret;
+    return len;
 }
 
 int mp_hal_stdin_rx_chr(void) {

ports/esp32/mphalport.c

@@ -120,25 +120,32 @@ int mp_hal_stdin_rx_chr(void) {
 }
 
 mp_uint_t mp_hal_stdout_tx_strn(const char *str, size_t len) {
-    mp_uint_t ret = len;
     // Only release the GIL if many characters are being sent
+    mp_uint_t ret = len, did_write = 0;
     bool release_gil = len > 20;
     if (release_gil) {
         MP_THREAD_GIL_EXIT();
     }
     #if CONFIG_ESP_CONSOLE_USB_SERIAL_JTAG
     usb_serial_jtag_tx_strn(str, len);
+    did_write = 1;
     #elif CONFIG_USB_OTG_SUPPORTED
     usb_tx_strn(str, len);
+    did_write = 1;
     #endif
     #if MICROPY_HW_ENABLE_UART_REPL
     uart_stdout_tx_strn(str, len);
+    did_write = 1;
     #endif
     if (release_gil) {
         MP_THREAD_GIL_ENTER();
     }
-    mp_os_dupterm_tx_strn(str, ret);
-    return ret;
+    int dupterm_res = mp_os_dupterm_tx_strn(str, len);
+    if (dupterm_res >= 0) {
+        did_write = 1;
+        ret = MIN((mp_uint_t)dupterm_res, ret);
+    }
+    return did_write?ret:0;
 }
 
 uint32_t mp_hal_ticks_ms(void) {

ports/esp8266/esp_mphal.c

@@ -95,9 +95,13 @@ void mp_hal_debug_str(const char *str) {
 #endif
 
 mp_uint_t mp_hal_stdout_tx_strn(const char *str, uint32_t len) {
-    mp_uint_t ret = len;
-    mp_os_dupterm_tx_strn(str, ret);
-    return ret;
+    int dupterm_res = mp_os_dupterm_tx_strn(str, len);
+    if (dupterm_res < 0) {
+        // no outputs, nothing was written
+        return 0;
+    } else {
+        return dupterm_res;
+    }
 }
 
 void mp_hal_debug_tx_strn_cooked(void *env, const char *str, uint32_t len) {

ports/mimxrt/mphalport.c

@@ -113,9 +113,10 @@ int mp_hal_stdin_rx_chr(void) {
 }
 
 mp_uint_t mp_hal_stdout_tx_strn(const char *str, mp_uint_t len) {
-    mp_uint_t ret = len;
+    mp_uint_t ret = len, did_write = 0;
     if (tud_cdc_connected()) {
-        for (size_t i = 0; i < len;) {
+        size_t i = 0;
+        while (i < len) {
             uint32_t n = len - i;
             if (n > CFG_TUD_CDC_EP_BUFSIZE) {
                 n = CFG_TUD_CDC_EP_BUFSIZE;
@@ -134,11 +135,17 @@ mp_uint_t mp_hal_stdout_tx_strn(const char *str, mp_uint_t len) {
             tud_cdc_write_flush();
             i += n2;
         }
+        did_write = 1;
+        ret = MIN(i, ret);
     }
     #if MICROPY_PY_OS_DUPTERM
-    mp_os_dupterm_tx_strn(str, ret);
+    int dupterm_res = mp_os_dupterm_tx_strn(str, len);
+    if (dupterm_res >= 0) {
+        did_write = 1;
+        ret = MIN((mp_uint_t)dupterm_res, ret);
+    }
     #endif
-    return ret;
+    return did_write?ret:0;
 }
 
 uint64_t mp_hal_time_ns(void) {

ports/minimal/uart_core.c

@@ -34,8 +34,8 @@ mp_uint_t mp_hal_stdout_tx_strn(const char *str, mp_uint_t len) {
     #if MICROPY_MIN_USE_STDOUT
     int r = write(STDOUT_FILENO, str, len);
     if (r >= 0) {
-        // in case of an error in the syscall, pretend write succeeded
-        ret = r;
+        // in case of an error in the syscall, report no bytes written
+        ret = 0;
     }
     #elif MICROPY_MIN_USE_STM32_MCU
     while (len--) {

ports/nrf/drivers/bluetooth/ble_uart.c

@@ -111,10 +111,10 @@ int mp_hal_stdin_rx_chr(void) {
 }
 
 mp_uint_t mp_hal_stdout_tx_strn(const char *str, size_t len) {
-    mp_uint_t ret = len;
     // Not connected: drop output
-    if (!ble_uart_enabled()) return ret;
+    if (!ble_uart_enabled()) return 0;
 
+    mp_uint_t ret = len;
     uint8_t *buf = (uint8_t *)str;
     size_t send_len;
 

ports/nrf/drivers/usb/usb_cdc.c

@@ -232,12 +232,11 @@ int mp_hal_stdin_rx_chr(void) {
 }
 
 mp_uint_t mp_hal_stdout_tx_strn(const char *str, mp_uint_t len) {
-    mp_uint_t ret = len;
     for (const char *top = str + len; str < top; str++) {
         ringbuf_put((ringbuf_t*)&tx_ringbuf, *str);
         usb_cdc_loop();
     }
-    return ret;
+    return len;
 }
 
 void mp_hal_stdout_tx_strn_cooked(const char *str, mp_uint_t len) {

ports/nrf/mphalport.c

@@ -197,11 +197,11 @@ int mp_hal_stdin_rx_chr(void) {
 }
 
 mp_uint_t mp_hal_stdout_tx_strn(const char *str, mp_uint_t len) {
-    mp_uint_t ret = len;
     if (MP_STATE_PORT(board_stdio_uart) != NULL) {
         uart_tx_strn(MP_STATE_PORT(board_stdio_uart), str, len);
+        return len;
     }
-    return ret;
+    return 0;
 }
 
 void mp_hal_stdout_tx_strn_cooked(const char *str, mp_uint_t len) {

ports/powerpc/uart_lpc_serial.c

@@ -109,13 +109,12 @@ int mp_hal_stdin_rx_chr(void) {
 
 
 mp_uint_t mp_hal_stdout_tx_strn(const char *str, mp_uint_t len) {
-    mp_uint_t ret = len;
     int i;
     for (i = 0; i < len; i++) {
         while (lpc_uart_tx_full()) {
             ;
         }
         lpc_uart_reg_write(REG_RBR, str[i]);
     }
-    return ret;
+    return len;
 }

ports/powerpc/uart_potato.c

@@ -119,7 +119,6 @@ int mp_hal_stdin_rx_chr(void) {
 }
 
 mp_uint_t mp_hal_stdout_tx_strn(const char *str, mp_uint_t len) {
-    mp_uint_t ret = len;
     int i;
 
     for (i = 0; i < len; i++) {
@@ -130,5 +129,5 @@ mp_uint_t mp_hal_stdout_tx_strn(const char *str, mp_uint_t len) {
         }
         potato_uart_reg_write(POTATO_CONSOLE_TX, val);
     }
-    return ret;
+    return len;
 }