Enable minimal-printf by default for all builds

TESTS/mbed_drivers/c_strings/main.cpp

@@ -116,14 +116,15 @@ Case cases[] = {
     Case("C strings: %u %d integer formatting", test_case_c_string_u_d, greentea_failure_handler),
     Case("C strings: %x %E integer formatting", test_case_c_string_x_X, greentea_failure_handler),
 #if !defined(__NEWLIB_NANO)
-    //In build tools, GCC with Newlib-nano linker option "-u _printf_float" is not configured
-    //to enable printf floating format. So disabling floating format test case.
+    // Newlib-nano linker option "-u _printf_float" is not set to enable floating point support.
+#if (defined(MBED_MINIMAL_PRINTF) && MBED_CONF_PLATFORM_MINIMAL_PRINTF_ENABLE_FLOATING_POINT) || !defined(MBED_MINIMAL_PRINTF)
     Case("C strings: %f %f float formatting", test_case_c_string_f_f, greentea_failure_handler),
+#endif
 #ifndef MBED_MINIMAL_PRINTF
     Case("C strings: %e %E float formatting", test_case_c_string_e_E, greentea_failure_handler),
     Case("C strings: %g %g float formatting", test_case_c_string_g_g, greentea_failure_handler),
-#endif
-#endif
+#endif // MBED_MINIMAL_PRINTF
+#endif // !defined(__NEWLIB_NANO)
 };
 
 utest::v1::status_t greentea_test_setup(const size_t number_of_cases)

TESTS/mbed_drivers/reset_reason/main.cpp

@@ -75,7 +75,7 @@ static cmd_status_t handle_command(const char *key, const char *value)
         int raw_reason_hex_str_len = snprintf(raw_reason_hex_str,
                                               sizeof raw_reason_hex_str, "%08lx", raw_reason);
 
-        if (raw_reason_hex_str_len != (sizeof raw_reason_hex_str) - 1) {
+        if (raw_reason_hex_str_len < 0) {
             TEST_ASSERT_MESSAGE(0, "Failed to compose raw reset reason hex string.");
             return CMD_STATUS_ERROR;
         }
@@ -134,7 +134,7 @@ void test_reset_reason()
     hal_reset_reason_get_capabilities(&rrcap);
     char msg_value[11];
     int str_len = snprintf(msg_value, sizeof msg_value, "%08lx,%01x", rrcap.reasons, MSG_VALUE_WATCHDOG_STATUS);
-    if (str_len != (sizeof msg_value) - 1) {
+    if (str_len < 0) {
         printf("Failed to compose a value string to be sent to host.");
         GREENTEA_TESTSUITE_RESULT(0);
         return;

TESTS/mbed_drivers/watchdog_reset/main.cpp

@@ -92,7 +92,7 @@ bool send_reset_notification(testcase_data *tcdata, uint32_t delay_ms)
 {
     char msg_value[12];
     int str_len = snprintf(msg_value, sizeof msg_value, "%02x,%08lx", tcdata->start_index + tcdata->index, delay_ms);
-    if (str_len != (sizeof msg_value) - 1) {
+    if (str_len < 0) {
         utest_printf("Failed to compose a value string to be sent to host.");
         return false;
     }

TESTS/mbed_hal/reset_reason/main.cpp

@@ -75,7 +75,7 @@ static cmd_status_t handle_command(const char *key, const char *value)
         int raw_reason_hex_str_len = snprintf(raw_reason_hex_str,
                                               sizeof raw_reason_hex_str, "%08lx", raw_reason);
 
-        if (raw_reason_hex_str_len != (sizeof raw_reason_hex_str) - 1) {
+        if (raw_reason_hex_str_len < 0) {
             TEST_ASSERT_MESSAGE(0, "Failed to compose raw reset reason hex string.");
             return CMD_STATUS_ERROR;
         }
@@ -129,7 +129,7 @@ void test_reset_reason()
     hal_reset_reason_get_capabilities(&rrcap);
     char msg_value[11];
     int str_len = snprintf(msg_value, sizeof msg_value, "%08lx,%01x", rrcap.reasons, MSG_VALUE_WATCHDOG_STATUS);
-    if (str_len != (sizeof msg_value) - 1) {
+    if (str_len < 0) {
         printf("Failed to compose a value string to be sent to host.");
         GREENTEA_TESTSUITE_RESULT(0);
         return;

TESTS/mbed_hal/watchdog_reset/main.cpp

@@ -90,7 +90,7 @@ bool send_reset_notification(testcase_data *tcdata, uint32_t delay_ms)
 {
     char msg_value[12];
     int str_len = snprintf(msg_value, sizeof msg_value, "%02x,%08lx", tcdata->start_index + tcdata->index, delay_ms);
-    if (str_len != (sizeof msg_value) - 1) {
+    if (str_len < 0) {
         utest_printf("Failed to compose a value string to be sent to host.");
         return false;
     }

TESTS/mbed_hal/watchdog_timing/main.cpp

@@ -59,7 +59,7 @@ bool send_reset_notification(testcase_data *tcdata, uint32_t delay_ms)
 {
     char msg_value[12];
     int str_len = snprintf(msg_value, sizeof msg_value, "%02x,%08lx", tcdata->start_index + tcdata->index, delay_ms);
-    if (str_len != (sizeof msg_value) - 1) {
+    if (str_len < 0) {
         utest_printf("Failed to compose a value string to be sent to host.");
         return false;
     }
@@ -110,7 +110,7 @@ void test_timing()
 
         int str_len = snprintf(msg_value, sizeof msg_value, "%02x,%08lx", current_case.start_index + current_case.index,
                                (uint32_t) current_ts);
-        if (str_len != (sizeof msg_value) - 1) {
+        if (str_len < 0) {
             utest_printf("Failed to compose a value string to be sent to host.");
             return;
         }

TESTS/mbed_timing_fpga_ci_test_shield/watchdog/main.cpp

@@ -119,7 +119,7 @@ bool send_reset_notification(testcase_data *tcdata, uint32_t delay_ms)
 {
     char msg_value[12];
     int str_len = snprintf(msg_value, sizeof msg_value, "%02x,%08lx", tcdata->start_index + tcdata->index, delay_ms);
-    if (str_len != (sizeof msg_value) - 1) {
+    if (str_len < 0) {
         utest_printf("Failed to compose a value string to be sent to host.");
         return false;
     }

platform/mbed_lib.json

@@ -140,15 +140,15 @@
             "value": true
         },
         "minimal-printf-enable-64-bit": {
-            "help": "Enable printing 64 bit integers when using mprintf profile",
+            "help": "Enable printing 64 bit integers when using minimal printf library",
             "value": true
         },
         "minimal-printf-enable-floating-point": {
-            "help": "Enable floating point printing when using mprintf profile",
+            "help": "Enable floating point printing when using minimal printf library",
             "value": false
         },
         "minimal-printf-set-floating-point-max-decimals": {
-            "help": "Maximum number of decimals to be printed",
+            "help": "Maximum number of decimals to be printed when using minimal printf library",
             "value": 6
         }
     },

platform/source/minimal-printf/README.md

@@ -1,7 +1,7 @@
 # Minimal printf and snprintf
 
 
-Library supports both printf and snprintf in 1252 bytes of flash.
+Library supports both printf and snprintf in around 1300 bytes of flash.
 
 Prints directly to stdio/UART without using malloc. All flags and precision modifiers are ignored.
 There is no error handling if a writing error occurs.
@@ -20,6 +20,10 @@ Supports:
 * %s: string.
 * %p: pointer (e.g. 0x00123456).
 
+Note that support for:
+* 64b modifiers is only present when `minimal-printf-enable-64-bit` config is set to `true` (default).
+* Floating point parameters is only present when `minimal-printf-enable-floating-point` config is set to `true` (disabled by default).
+
 Unrecognized format specifiers are treated as ordinary characters.
 
 Floating point limitations:
@@ -28,8 +32,7 @@ Floating point limitations:
 
 ## Usage
 
-
-To replace the standard implementation of the printf functions with the ones in this library:
+As of Mbed OS 6.0 this is enabled by default. To replace the standard implementation of the printf functions with the ones in this library for older versions of Mbed:
 
 Modify your application configuration file to override the parameter `target.printf_lib` with the value `minimal-printf` as shown below:
 
@@ -43,6 +46,17 @@ Modify your application configuration file to override the parameter `target.pri
 }
 ```
 
+If your application requires more advanced functionality, you'll need to revert to using standard version of printf/snprintf. Please note that it will result in significant ROM usage increase. In case you are using minimal version of standard C library advanced functionality may not be present.
+
+Modify your application configuration in `mbed_app.json` file to override the parameter `target.printf_lib` with the value `std` as shown below:
+
+```json
+    "target_overrides": {
+        "*": {
+            "target.printf_lib": "std"
+        }
+    }
+```
 
 ## Configuration
 
@@ -54,27 +68,24 @@ Minimal printf is configured by the following parameters defined in `platform/mb
     "name": "platform",
     "config": {
         "minimal-printf-enable-64-bit": {
-            "help": "Enable printing 64 bit integers when using minimal-printf profile",
+            "help": "Enable printing 64 bit integers when using minimal printf library",
             "value": true
         },
         "minimal-printf-enable-floating-point": {
-            "help": "Enable floating point printing when using minimal-printf profile",
+            "help": "Enable floating point printing when using minimal printf library",
             "value": false
         },
         "minimal-printf-set-floating-point-max-decimals": {
-            "help": "Maximum number of decimals to be printed",
+            "help": "Maximum number of decimals to be printed when using minimal printf library",
             "value": 6
         }
-   }
+    }
 }
 ```
 
-By default, 64 bit integers support is enabled.
-
-If your target does not require some options then you can override the default configuration in your application `mbed_app.json` and achieve further memory optimisation (see next section for size comparison numbers).
-
-In mbed_app.json:
+By default, 64 bit integers support is enabled, but floating point support is disabled to increase memory savings.
 
+If your application needs to override the default configuration add following section to your `mbed_app.json`:
 ```json
     "target_overrides": {
         "*": {

platform/source/minimal-printf/mbed_printf_implementation.c

@@ -1,5 +1,5 @@
 /* mbed Microcontroller Library
- * Copyright (c) 2017 ARM Limited
+ * Copyright (c) 2017-2020 ARM Limited
  * SPDX-License-Identifier: Apache-2.0
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -122,17 +122,22 @@ static void mbed_minimal_putchar(char *buffer, size_t length, int *result, char
 {
     /* only continue if 'result' doesn't overflow */
     if ((*result >= 0) && (*result <= INT_MAX - 1)) {
-        /* write data only if there's enough space */
-        if ((size_t)*result < length) {
-            if (buffer) {
+        if (buffer) {
+            /* write data only if there's enough space */
+            if ((size_t)*result < length) {
                 buffer[*result] = data;
+            }
+
+            /* increment 'result' even if data was not written. This ensures that
+               'mbed_minimal_formatted_string' returns the correct value. */
+            *result += 1;
+        } else {
+            if (fputc(data, stream) == EOF) {
+                *result = EOF;
             } else {
-                fputc(data, stream);
+                *result += 1;
             }
         }
-        /* increment 'result' even if data was not written. This ensures that
-           'mbed_minimal_formatted_string' returns the correct value. */
-        *result += 1;
     }
 }
 
@@ -503,6 +508,16 @@ int mbed_minimal_formatted_string(char *buffer, size_t length, const char *forma
                         /* use 64 bit storage type for readout */
                         value = va_arg(arguments, MBED_SIGNED_STORAGE);
                     } else
+#else
+                    /* If 64 bit is not enabled, print %ll[di] rather than truncated value */
+                    if (length_modifier == LENGTH_LL) {
+                        mbed_minimal_formatted_string_character(buffer, length, &result, '%', stream);
+                        if (next == '%') {
+                            // Continue printing loop after `%`
+                            index = next_index;
+                        }
+                        continue;
+                    }
 #endif
                     {
                         /* use native storage type (which can be 32 or 64 bit) */
@@ -552,6 +567,16 @@ int mbed_minimal_formatted_string(char *buffer, size_t length, const char *forma
                         /* use 64 bit storage type for readout */
                         value = va_arg(arguments, MBED_UNSIGNED_STORAGE);
                     } else
+#else
+                    /* If 64 bit is not enabled, print %ll[uxX] rather than truncated value */
+                    if (length_modifier == LENGTH_LL) {
+                        mbed_minimal_formatted_string_character(buffer, length, &result, '%', stream);
+                        if (next == '%') {
+                            // Continue printing loop after `%`
+                            index = next_index;
+                        }
+                        continue;
+                    }
 #endif
                     {
                         /* use native storage type (which can be 32 or 64 bit) */

targets/targets.json

@@ -19,7 +19,7 @@
         "c_lib": "std",
         "bootloader_supported": false,
         "static_memory_defines": true,
-        "printf_lib": "std",
+        "printf_lib": "minimal-printf",
         "supported_c_libs": {
             "arm": [
                 "std"