Add more docs

dev/VisualStudio/main.c

@@ -12,7 +12,9 @@
  */
 int
 lwprintf_output(int ch, lwprintf_t* lw) {
-    printf("%c", (char)ch);
+    if (ch != '\0') {
+        printf("%c", (char)ch);
+    }
     return ch;
 }
 
@@ -68,8 +70,9 @@ main(void) {
     lwprintf_init(lwprintf_output);
 
     /* Float tests */
-    for (float a = 0.0f; a < 1.0f; a += 0.01f) {
-        printf_run(NULL, "%10f; %10.1f; %10.0f", 1.99f + a, 1.99f + a, 1.99f + a);
+    for (float a = 0.0f; a < 2.0f; a += 0.01f) {
+        printf_run(NULL, "%10f; %10.1f; %10.0f; %+10f", 1.99f + a, 1.99f + a, 1.99f + a, 1.99 + a);
+        printf_run(NULL, "%10f; %10.1f; %10.0f; %+10f", -1.99f + a, -1.99f + a, -1.99f + a, -1.99 + a);
     }
     return 0;
 

docs/examples_src/example_instance.c

@@ -0,0 +1,40 @@
+#include "lwprintf/lwprintf.h"
+
+/* Define application custom instance */
+lwprintf_t custom_instance;
+
+/* Define custom output function for print */
+int
+custom_out(int ch, lwprintf_t* p) {
+    /* Do whatever with this character */
+    if (ch == '\0') {
+        /* This is end of string in current formatting */
+        /* Maybe time to start DMA transfer? */
+    } else {
+        /* Print or send character */
+    }
+
+    /* Return character to proceed */
+    return ch;
+}
+
+/* Define output function for default instance */
+int
+default_out(int ch, lwprintf_t* p) {
+    /* Print function for default instance */
+
+    /* See custom_out function for implementation details */
+}
+
+int
+main(void) {
+    /* Initialize default lwprintf instance with output function */
+    lwprintf_init(default_out);
+    /* Initialize custom lwprintf instance with output function */
+    lwprintf_init_ex(&custom_instance, custom_out);
+
+    /* Print first text over default output */
+    lwprintf_printf("Text: %d", 10);
+    /* Print text over custom instance */
+    lwprintf_printf_ex(&custom_instance, "Custom: %f", 3.2f);
+}

docs/examples_src/example_instance_single_func.c

@@ -0,0 +1,28 @@
+#include "lwprintf/lwprintf.h"
+
+/* Define application custom instance */
+lwprintf_t custom_instance1;
+lwprintf_t custom_instance2;
+
+/* Define custom output function for print */
+int
+my_out(int ch, lwprintf_t* p) {
+    if (p == &custom_instance1) {
+        /* This is custom instance 1 */
+    } else if (p == &custom_instance2) {
+        /* This is custom instance 2 */
+    } else {
+        /* This is default instance */
+    }
+    return ch;
+}
+
+int
+main(void) {
+    /* Initialize default lwprintf instance with output function */
+    lwprintf_init(my_out);
+    lwprintf_init_ex(&custom_instance1, my_out);
+    lwprintf_init_ex(&custom_instance2, my_out);
+
+    /* Use print functions ... */
+}

docs/examples_src/example_minimal.c

@@ -4,7 +4,9 @@
 int
 lwprintf_out(int ch, lwprintf_t* lwp) {
     /* May use printf to output it for test */
-    printf("%c", (char)ch);
+    if (ch != '\0') {
+    	printf("%c", (char)ch);
+    }
 
     return ch;
 }

docs/user-manual/how-it-works.rst

@@ -3,7 +3,29 @@
 How it works
 ============
 
-To be added
+LwPRINTF library supports ``2`` different formatting output types:
+
+* Write formatted data to user input array
+* Directly print formatted characters by calling ``output_function`` for every formatted character in the input string
+
+Text formatting is based on input format string followed by the data parameters.
+It is mostly used to prepare numeric data types to human readable format.
+
+.. note::
+    LwPRINTF is open-source implementation of regular *stdio.h* library in C language.
+    It implements only output functions, excluding input scanning features
+
+Formatting functions take input *format string* followed by (optional) different data types.
+Internal algorithm scans character by character to understand type of expected data user would like to have printed.
+
+Every format specifier starts with letter ``%``, followed by optional set of flags, widths and other sets of characters.
+Last part of every specifier is its type, that being type of format and data to display.
+
+.. tip::
+    To print number ``1234`` in human readable format, use specifier ``%d``.
+    With default configuration, call ``lwprintf_printf("%d", 1234);`` and it will print ``"1234"``.
+
+Check section :ref:`um_format_specifier` for list of all formats and data types
 
 .. toctree::
     :maxdepth: 2

docs/user-manual/index.rst

@@ -6,5 +6,7 @@ User manual
 .. toctree::
     :maxdepth: 2
 
+    how-it-works
     format-specifier
+    instances
     thread-safety

docs/user-manual/instances.rst

@@ -3,10 +3,36 @@
 LwPRINTF instances
 ==================
 
-LwPRINTF architecture allows multiple instances...
+LwPRINTF is very flexible and allows multiple instances for output print functions.
 
-To be added..
+.. note::
+    Multiple instances with LwPRINTF are useful only with direct
+    print functions, suchs as :c:macro:`lwprintf_printf`.
+    If application uses only format functions which write to input buffer,
+    it may always use default LwPRINTF instance which is
+    created by the library itself
 
+Use of different instances is useful if application needs different print
+configurations. Each instance has its own ``print_output`` function,
+allowing application to use multiple debug configurations (as an example)
+
+.. tip::
+    Use functions with ``_ex`` suffix to direcly work with custom instances.
+    Functions without ``_ex`` suffix use default LwPRINTF instance
+
+.. literalinclude:: ../examples_src/example_instance.c
+    :language: c
+    :linenos:
+    :caption: Custom LwPRINTF instance for output
+
+.. note::
+    It is perfectly valid to use single output function for all application instances.
+    Use check against input parameter for :c:type:`lwprintf_t` if it matches your custom LwPRINTF instance memory address
+
+.. literalinclude:: ../examples_src/example_instance_single_func.c
+    :language: c
+    :linenos:
+    :caption: Single output function for all LwPRINTF instances
 
 .. toctree::
     :maxdepth: 2