kolibrios-gitea/drivers/ddk/string/_strnlen.S
Sergey Semyonov (Serge) 1402c59305 ddk: tiny libc and kernel imports library
git-svn-id: svn://kolibrios.org@1408 a494cfbc-eb01-0410-851d-a64ba20cac60
2010-02-12 20:11:35 +00:00

31 lines
823 B
ArmAsm

# _strnlen() Author: Kees J. Bot 1 Jan 1994
# size_t _strnlen(const char *s, size_t ecx)
# Return the length of a string.
.intel_syntax
.globl __strnlen
.text
.align 16
__strnlen:
push ebp
mov ebp, esp
push edi
mov edi, [ebp+8] # edi = string
xorb al, al # Look for a zero byte
mov edx, ecx # Save maximum count
cmpb cl, 1 # 'Z' bit must be clear if ecx = 0
cld
repne
scasb # Look for zero
jne no0
inc ecx # Don't count zero byte
no0:
mov eax, edx
sub eax, ecx # Compute bytes scanned
pop edi
pop ebp
ret