| 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 |
|---|
