minix/lib/libminlib/i386/oneC_sum.S
Ben Gras 2fe8fb192f Full switch to clang/ELF. Drop ack. Simplify.
There is important information about booting non-ack images in
docs/UPDATING. ack/aout-format images can't be built any more, and
booting clang/ELF-format ones is a little different. Updating to the
new boot monitor is recommended.

Changes in this commit:

	. drop boot monitor -> allowing dropping ack support
	. facility to copy ELF boot files to /boot so that old boot monitor
	  can still boot fairly easily, see UPDATING
	. no more ack-format libraries -> single-case libraries
	. some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases
	. drop several ack toolchain commands, but not all support
	  commands (e.g. aal is gone but acksize is not yet).
	. a few libc files moved to netbsd libc dir
	. new /bin/date as minix date used code in libc/
	. test compile fix
	. harmonize includes
	. /usr/lib is no longer special: without ack, /usr/lib plays no
	  kind of special bootstrapping role any more and bootstrapping
	  is done exclusively through packages, so releases depend even
	  less on the state of the machine making them now.
	. rename nbsd_lib* to lib*
	. reduce mtree
2012-02-14 14:52:02 +01:00

88 lines
1.9 KiB
ArmAsm

/* oneC_sum() - One complement`s checksum Author: Kees J. Bot */
/* 9 May 1995 */
/* See RFC 1071, "Computing the Internet checksum" */
/* See also the C version of this code. */
#include <machine/asm.h>
ENTRY(oneC_sum)
push %ebp
movl %esp, %ebp
push %esi
push %edi
movzwl 8(%ebp), %eax /* Checksum of previous block */
movl 12(%ebp), %esi /* Data to compute checksum over */
movl 16(%ebp), %edi /* Number of bytes */
xorl %edx, %edx
xorb %cl, %cl
align:
testl $3, %esi /* Is the data aligned? */
je aligned
testl %edi, %edi
je 0f
movb (%esi), %dl /* Rotate the first unaligned bytes */
decl %edi /* into the edx register */
0:
incl %esi
rorl $8, %edx
rorl $8, %eax /* Rotate the checksum likewise */
addb $8, %cl /* Number of bits rotated */
jmp align
aligned:
addl %edx, %eax /* Summate the unaligned bytes */
adcl $0, %eax /* Add carry back in for one`s complement */
jmp add6test
_ALIGN_TEXT
add6:
addl (%esi), %eax /* Six times unrolled loop, see below */
adcl 4(%esi), %eax
adcl 8(%esi), %eax
adcl 12(%esi), %eax
adcl 16(%esi), %eax
adcl 20(%esi), %eax
adcl $0, %eax
addl $24, %esi
add6test:
subl $24, %edi
jae add6
addl $24, %edi
jmp add1test
_ALIGN_TEXT
add1:
addl (%esi), %eax /* while ((edi -= 4) >= 0) */
adcl $0, %eax /* eax += *esi++; */
addl $4, %esi /* edi += 4; */
add1test:
subl $4, %edi
jae add1
addl $4, %edi
je done /* Are there extra bytes? */
movl (%esi), %edx /* Load extra bytes in a full dword */
andl mask-4(,%edi,4), %edx /* Mask off excess */
addl %edx, %eax /* Add in the last bits */
adcl $0, %eax
done:
roll %cl, %eax /* Undo the rotation at the beginning */
movl %eax, %edx
shrl $16, %eax
addw %dx, %ax /* Add the two words in eax to form */
adcw $0, %ax /* a 16 bit sum */
pop %edi
pop %esi
pop %ebp
ret
#ifdef __ACK__
.rom
#else
.data
#endif
.balign 4
mask:
.long 0x000000FF, 0x0000FFFF, 0x00FFFFFF
/* */
/* $PchId: oneC_sum.ack.s,v 1.2 1996/03/12 19:33:51 philip Exp $ */