--- /dev/null
+/*
+ * INET An implementation of the TCP/IP protocol suite for the LINUX
+ * operating system. INET is implemented using the BSD Socket
+ * interface as the means of communication with the user level.
+ *
+ * IP/TCP/UDP checksumming routines
+ *
+ * Authors: Jorge Cwik, <jorge@laser.satlink.net>
+ * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
+ * Tom May, <ftom@netcom.com>
+ * Pentium Pro/II routines:
+ * Alexander Kjeldaas <astor@guardian.no>
+ * Finn Arne Gangstad <finnag@guardian.no>
+ * Lots of code moved from tcp.c and ip.c; see those files
+ * for more names.
+ *
+ * Changes: Ingo Molnar, converted csum_partial_copy() to 2.1 exception
+ * handling.
+ * Andi Kleen, add zeroing on error
+ * converted to pure assembler
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+/*
+ * computes a partial checksum, e.g. for TCP/UDP fragments
+ */
+
+/*
+unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum)
+ */
+
+#include <asm.inc>
+
+.code
+.align 4
+PUBLIC _csum_partial
+
+#ifndef CONFIG_X86_USE_PPRO_CHECKSUM
+
+ /*
+ * Experiments with Ethernet and SLIP connections show that buff
+ * is aligned on either a 2-byte or 4-byte boundary. We get at
+ * least a twofold speedup on 486 and Pentium if it is 4-byte aligned.
+ * Fortunately, it is easy to convert 2-byte alignment to 4-byte
+ * alignment for the unrolled loop.
+ */
+_csum_partial:
+ push esi
+ push ebx
+ mov eax, [esp + 20] // Function arg: unsigned int sum
+ mov ecx, [esp + 16] // Function arg: int len
+ mov esi, [esp + 12] // Function arg: unsigned char *buff
+ test esi, 3 // Check alignment.
+ jz m2 // Jump if alignment is ok.
+ test esi, 1 // Check alignment.
+ jz l10 // Jump if alignment is boundary of 2bytes.
+
+ // buf is odd
+ dec ecx
+ jl l8
+ movzx ebx, byte ptr [esi]
+ adc eax, ebx
+ rol eax, 8
+ inc esi
+ test esi, 2
+ jz m2
+l10:
+ sub ecx, 2 // Alignment uses up two bytes.
+ jae m1 // Jump if we had at least two bytes.
+ add ecx, 2 // ecx was < 2. Deal with it.
+ jmp l4
+m1: mov bx, [esi]
+ add esi, 2
+ add ax, bx
+ adc eax, 0
+m2:
+ mov edx, ecx
+ shr ecx, 5
+ jz l2
+ test esi, esi
+l1: mov ebx, [esi]
+ adc eax, ebx
+ mov ebx, [esi + 4]
+ adc eax, ebx
+ mov ebx, [esi + 8]
+ adc eax, ebx
+ mov ebx, [esi + 12]
+ adc eax, ebx
+ mov ebx, [esi + 16]
+ adc eax, ebx
+ mov ebx, [esi + 20]
+ adc eax, ebx
+ mov ebx, [esi + 24]
+ adc eax, ebx
+ mov ebx, [esi + 28]
+ adc eax, ebx
+ lea esi, [esi + 32]
+ dec ecx
+ jne l1
+ adc eax, 0
+l2: mov ecx, edx
+ and edx, HEX(1c)
+ je l4
+ shr edx, 2 // This clears CF
+l3: adc eax, [esi]
+ lea esi, [esi + 4]
+ dec edx
+ jne l3
+ adc eax, 0
+l4: and ecx, 3
+ jz l7
+ cmp ecx, 2
+ jb l5
+ mov cx, [esi]
+ lea esi, [esi + 2]
+ je l6
+ shl ecx, 16
+l5: mov cl, [esi]
+l6: add eax, ecx
+ adc eax, 0
+l7:
+ test dword ptr [esp + 12], 1
+ jz l8
+ rol eax, 8
+l8:
+ pop ebx
+ pop esi
+ ret
+
+#else
+
+/* Version for PentiumII/PPro */
+
+csum_partial:
+ push esi
+ push ebx
+ mov eax, [esp + 20] # Function arg: unsigned int sum
+ mov ecx, [esp + 16] # Function arg: int len
+ mov esi, [esp + 12] # Function arg: const unsigned char *buf
+
+ test esi, 3
+ jnz l25f
+l10:
+ mov edx, ecx
+ mov ebx, ecx
+ and ebx, HEX(7c)
+ shr ecx, 7
+ add esi, ebx
+ shr ebx, 2
+ neg ebx
+ lea ebx, l45[ebx + ebx * 2]
+ test esi, esi
+ jmp dword ptr [ebx]
+
+ // Handle 2-byte-aligned regions
+l20: add ax, [esi]
+ lea esi, [esi + 2]
+ adc eax, 0
+ jmp l10b
+l25:
+ test esi, 1
+ jz l30f
+ // buf is odd
+ dec ecx
+ jl l90
+ movzb ebx, [esi]
+ add eax, ebx
+ adc eax, 0
+ rol eax, 8
+ inc esi
+ test esi, 2
+ jz l10b
+
+l30: sub ecx, 2
+ ja l20
+ je l32
+ add ecx, 2
+ jz l80
+ movzb ebx, [esi] // csumming 1 byte, 2-aligned
+ add eax, ebx
+ adc eax, 0
+ jmp l80
+l32:
+ add ax, [esi] // csumming 2 bytes, 2-aligned
+ adc eax, 0
+ jmp l80
+
+l40:
+ add eax, [esi -128]
+ adc eax, [esi -124]
+ adc eax, [esi -120]
+ adc eax, [esi -116]
+ adc eax, [esi -112]
+ adc eax, [esi -108]
+ adc eax, [esi -104]
+ adc eax, [esi -100]
+ adc eax, [esi -96]
+ adc eax, [esi -92]
+ adc eax, [esi -88]
+ adc eax, [esi -84]
+ adc eax, [esi -80]
+ adc eax, [esi -76]
+ adc eax, [esi -72]
+ adc eax, [esi -68]
+ adc eax, [esi -64]
+ adc eax, [esi -60]
+ adc eax, [esi -56]
+ adc eax, [esi -52]
+ adc eax, [esi -48]
+ adc eax, [esi -44]
+ adc eax, [esi -40]
+ adc eax, [esi -36]
+ adc eax, [esi -32]
+ adc eax, [esi -28]
+ adc eax, [esi -24]
+ adc eax, [esi -20]
+ adc eax, [esi -16]
+ adc eax, [esi -12]
+ adc eax, [esi -8]
+ adc eax, [esi -4]
+l45:
+ lea esi, [esi + 128]
+ adc eax, 0
+ dec ecx
+ jge l40
+ mov ecx, edx
+l50: and ecx, 3
+ jz l80
+
+ // Handle the last 1-3 bytes without jumping
+ not ecx // 1->2, 2->1, 3->0, higher bits are masked
+ mov ebx, HEX(ffffff) // by the shll and shrl instructions
+ shl ecx, 3
+ shr ebx, cl
+ and ebx, [esi -128] // esi is 4-aligned so should be ok
+ add eax, ebx
+ adc eax, 0
+l80:
+ test dword ptr [esp + 12], 1
+ jz l90
+ rol eax, 8
+l90:
+ pop ebx
+ pop esi
+ ret
+
+#endif
+
+END
projects / reactos.git / blobdiff