diff options
Diffstat (limited to 'c/src/lib/libbsp/m32r/m32rsim/start/start.S')
| -rw-r--r-- | c/src/lib/libbsp/m32r/m32rsim/start/start.S | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/c/src/lib/libbsp/m32r/m32rsim/start/start.S b/c/src/lib/libbsp/m32r/m32rsim/start/start.S new file mode 100644 index 0000000000..065e64db79 --- /dev/null +++ b/c/src/lib/libbsp/m32r/m32rsim/start/start.S @@ -0,0 +1,58 @@ +/* + * From Newlib 1.16.0 + * + * $Id$ + */ + + .text + .balign 4 + .global _start +_start: + + seth sp, #shigh(_stack) + add3 sp, sp, #low(_stack) + ldi fp, #0 + +# Clear the BSS. Do it in two parts for efficiency: longwords first +# for most of it, then the remaining 0 to 3 bytes. + + seth r2, #shigh(__bss_start) + add3 r2, r2, #low(__bss_start); R2 = start of BSS + seth r3, #shigh(_end) + add3 r3, r3, #low(_end) ; R3 = end of BSS + 1 + + sub r3, r2 ; R3 = BSS size in bytes + mv r4, r3 + srli r4, #2 ; R4 = BSS size in longwords (rounded down) + ldi r1, #0 ; clear R1 for longword store + addi r2, #-4 ; account for pre-inc store + beqz r4, .Lendloop1 ; any more to go? +.Lloop1: + st r1, @+r2 ; yep, zero out another longword + addi r4, #-1 ; decrement count + bnez r4, .Lloop1 ; go do some more +.Lendloop1: + and3 r4, r3, #3 ; get no. of remaining BSS bytes to clear + addi r2, #4 ; account for pre-inc store + beqz r4, .Lendloop2 ; any more to go? +.Lloop2: + stb r1, @r2 ; yep, zero out another byte + addi r2, #1 ; bump address + addi r4, #-1 ; decrement count + bnez r4, .Lloop2 ; go do some more +.Lendloop2: + +# Run code in the .init section. +# This will queue the .fini section to be run with atexit. + + # bl __init + +# Call main, then exit. + + bl boot_card + bl sys_exit + +# If that fails just loop. + +.Lexit: + bra .Lexit |