These directives associate portions of an assembly language program with the appropriate sections:

• The .bss directive reserves space in the .bss section for uninitialized variables.
• The .clink directive enables conditional linking by telling the linker to leave the named section out of the final object module output of the linker if there are no references found to any symbol in the section. The .clink directive can be applied to initialized sections. (COFF only)
• The .data directive identifies portions of code in the .data section. The .data section usually contains initialized data.
• The .retain directive can be used to indicate that the current or specified section must be included in the linked output. Thus even if no other sections included in the link reference the current or specified section, it is still included in the link. (EABI only)
• The .retainrefs directive can be used to force sections that refer to the specified section. This is useful in the case of interrupt vectors. (EABI only)
• The .sect directive defines an initialized named section and associates subsequent code or data with that section. A section defined with .sect can contain code or data.
• The .text directive identifies portions of code in the .text section. The .text section usually contains executable code.
• The .usect directive reserves space in an uninitialized named section. The .usect directive is similar to the .bss directive, but it allows you to reserve space separately from the .bss section.

Chapter 3 discusses these sections in detail.

The example that follows shows how you can use sections directives to associate code and data with the proper sections. This is an output listing; column 1 shows line numbers, and column 2 shows the SPC values. (Each section has its own program counter, or SPC.) When code is first placed in a section, its SPC equals 0. When you resume assembling into a section after other code is assembled, the section's SPC resumes counting as if there had been no intervening code.

The directives in this example perform the following tasks:

The .bss and .usect directives do not end the current section or begin new sections; they reserve the specified amount of space, and then the assembler resumes assembling code or data into the current section.

       1              ***************************************************
       2              *     Start assembling into the .text section     *
       3              ***************************************************
       4 000000               .text
       5 000000 0001          .word   1, 2
         000001 0002 
       6 000002 0003          .word   3, 4
         000003 0004 
       7              
       8              ***************************************************
       9              *     Start assembling into the .data section     *
      10              ***************************************************
      11 000000               .data
      12 000000 0009          .word   9, 10
         000001 000A 
      13 000002 000B          .word   11, 12
         000003 000C 
      14              
      15              ***************************************************
      16              *     Start assembling into a named,              *
      17              *     initialized section, var_defs               *
      18              ***************************************************
      19 000000               .sect   "var_defs"
      20 000000 0011          .word   17, 18
         000001 0012 
      21              
      22              ***************************************************
      23              *     Resume assembling into the .data section    *
      24              ***************************************************
      25 000004               .data
      26 000004 000D          .word   13, 14
         000005 000E 
      27 000000       sym     .usect  ".ebss", 19 ; Reserve space in .ebss
      28 000006 000F          .word   15, 16      ; Still in .data
         000007 0010 
      29              
      30              ***************************************************
      31              *     Resume assembling into the .text section    *
      32              ***************************************************
      33 000004               .text
      34 000004 0005          .word   5, 6
         000005 0006 
      35 000000       usym    .usect  "xy", 20   ; Reserve space in xy
      36 000006 0007          .word   7, 8       ; Still in .text 
      37 000007 0008