Add command to configure section padding

Author: igrr

README.md

@@ -26,7 +26,8 @@ Argument | Description
 ```-bz <512K|256K|1M|2M|4M|8M|16M|32M>``` | Set the flash chip size. Default is 512K.
 ```-bf <40|26|20|80>``` | Set the flash chip frequency, in MHz. Default is 40M.
 ```-bs <section>``` | Read the specified section from the ELF file and append it to the firmware image. Sections will appear in the firmware image in the exact same order as the -bs commands are executed.
-```-bp <size>``` | Pad last written section of firmware image to the given size, in bytes.
+```-bp <size>``` | Finalize the firmware image, padding it with `0xaa` value until it is at least `<size>` bytes long. Unlike `-bc`, this doesn't close the file. This option can be used to combine bootloader with the rest of the application
+```-br <size>``` | Pad all the following sections to multiples of `<size>`. Default is 4 bytes. This option can be used to place sections on specific boundaries, e.g. 4k or 64k.
 ```-bc``` | Close the firmware image and save the result as file to disk.
 ```-v``` | Increase verbosity level of the tool. Add more v's to increase it even more, e.g. -vv, -vvv.
 ```-q``` | Disable most of the output.

argparse/argparse.c

@@ -78,7 +78,13 @@ they are given.\n\
     same order as the -bs commands are executed.\n\
 \n\
 -bp <size>\n\
-    Pad last written section of firmware image to the given size, in bytes.\n\
+    Finalize the firmware image, padding it with '0xaa' value until it is at least\n\
+    <size> bytes long. Unlike -bc, this doesn't close the file.\n\
+    This option can be used to combine bootloader with the rest of the application\n\
+\n\
+-br <size>\n\
+    Pad all the following sections to multiples of <size>. Default is 4 bytes.\n\
+    This option can be used to place sections on specific boundaries, e.g. 4k or 64k.\n\
 \n\
 -bc\n\
     Close the firmware image and save the result as file to disk.\n\

argparse/argparse_binimagecmd.c

@@ -30,6 +30,8 @@
 #include "esptool_elf_object.h"
 #include "esptool_binimage.h"
 
+static unsigned section_pad_size = 4;
+
 static int argparse_binimagecmd_add_segment(const char *sname, uint32_t padsize)
 {
     uint32_t snum;
@@ -93,7 +95,7 @@ int argparse_binimagecmd(int num_args, char **arg_ptr)
                 {
                     return 0;
                 }
-                if(argparse_binimagecmd_add_segment(arg_ptr[0], 4))
+                if(argparse_binimagecmd_add_segment(arg_ptr[0], section_pad_size))
                 {
                     bimage_set_entry(get_elf_entry());
                     return 2;
@@ -119,6 +121,14 @@ int argparse_binimagecmd(int num_args, char **arg_ptr)
                 }
                 break;
 
+            case 'r':
+                if(num_args < 1)
+                {
+                    return 0;
+                }
+                section_pad_size = (unsigned) atoi(arg_ptr[0]);    
+                return 2;
+
             case 'm':
                 if (num_args < 1)
                 {