libgloss/m32r/crt0.S

   1         .text
   2         .balign 4
   3         .global _start
   4 _start:
   5
   6         seth    sp, #shigh(_stack)
   7         add3    sp, sp, #low(_stack)
   8         ldi     fp, #0
   9
  10 # Clear the BSS.  Do it in two parts for efficiency: longwords first
  11 # for most of it, then the remaining 0 to 3 bytes.
  12
  13         seth    r2, #shigh(__bss_start)
  14         add3    r2, r2, #low(__bss_start); R2 = start of BSS
  15         seth    r3, #shigh(_end)
  16         add3    r3, r3, #low(_end)      ; R3 = end of BSS + 1
  17
  18         sub     r3, r2          ; R3 = BSS size in bytes
  19         mv      r4, r3
  20         srli    r4, #2          ; R4 = BSS size in longwords (rounded down)
  21         ldi     r1, #0          ; clear R1 for longword store
  22         addi    r2, #-4         ; account for pre-inc store
  23         beqz    r4, .Lendloop1  ; any more to go?
  24 .Lloop1:
  25         st      r1, @+r2        ; yep, zero out another longword
  26         addi    r4, #-1         ; decrement count
  27         bnez    r4, .Lloop1     ; go do some more
  28 .Lendloop1:
  29         and3    r4, r3, #3      ; get no. of remaining BSS bytes to clear
  30         addi    r2, #4          ; account for pre-inc store
  31         beqz    r4, .Lendloop2  ; any more to go?
  32 .Lloop2:
  33         stb     r1, @r2         ; yep, zero out another byte
  34         addi    r2, #1          ; bump address
  35         addi    r4, #-1         ; decrement count
  36         bnez    r4, .Lloop2     ; go do some more
  37 .Lendloop2:
  38
  39 # Run code in the .init section.
  40 # This will queue the .fini section to be run with atexit.
  41
  42         bl      __init
  43
  44 # Call main, then exit.
  45
  46         bl      main
  47         bl      exit
  48
  49 # If that fails just loop.
  50
  51 .Lexit:
  52         bra     .Lexit