Commit | Line | Data |
---|---|---|
478db76b | 1 | ;/*++\r |
2 | ;\r | |
4ea9375a HT |
3 | ;Copyright (c) 2006, Intel Corporation. All rights reserved.<BR>\r |
4 | ;This program and the accompanying materials \r | |
478db76b | 5 | ;are licensed and made available under the terms and conditions of the BSD License \r |
6 | ;which accompanies this distribution. The full text of the license may be found at \r | |
7 | ;http://opensource.org/licenses/bsd-license.php \r | |
8 | ; \r | |
9 | ;THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, \r | |
10 | ;WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. \r | |
11 | ;\r | |
12 | ;Module Name:\r | |
13 | ;\r | |
14 | ; EfiZeroMem.c\r | |
15 | ;\r | |
16 | ;Abstract:\r | |
17 | ;\r | |
18 | ; This is the code that supports IA32-optimized ZeroMem service\r | |
19 | ;\r | |
20 | ;--*/\r | |
21 | ;---------------------------------------------------------------------------\r | |
22 | .686\r | |
23 | .model flat,C\r | |
24 | .mmx\r | |
25 | .code\r | |
26 | \r | |
27 | ;---------------------------------------------------------------------------\r | |
28 | ;VOID\r | |
29 | ;EfiCommonLibZeroMem (\r | |
30 | ; IN VOID *Buffer,\r | |
31 | ; IN UINTN Count\r | |
32 | ; )\r | |
33 | ;/*++\r | |
34 | ;\r | |
35 | ;Input: VOID *Buffer - Pointer to buffer to clear\r | |
36 | ; UINTN Count - Number of bytes to clear\r | |
37 | ;\r | |
38 | ;Output: None.\r | |
39 | ;\r | |
40 | ;Saves:\r | |
41 | ;\r | |
42 | ;Modifies:\r | |
43 | ;\r | |
44 | ;Description: This function is an optimized zero-memory function.\r | |
45 | ;\r | |
46 | ;Notes: This function tries to zero memory 8 bytes at a time. As a result, \r | |
47 | ; it first picks up any misaligned bytes, then words, before getting \r | |
48 | ; in the main loop that does the 8-byte clears.\r | |
49 | ;\r | |
50 | ;--*/\r | |
51 | EfiCommonLibZeroMem PROC\r | |
52 | ; UINT64 MmxSave;\r | |
53 | push ebp\r | |
54 | mov ebp, esp\r | |
55 | push ecx ; Reserve space for local variable MmxSave\r | |
56 | push ecx\r | |
57 | push edi\r | |
58 | \r | |
59 | mov ecx, [ebp + 0Ch] ; Count\r | |
60 | mov edi, [ebp + 8]; Buffer\r | |
61 | \r | |
62 | ; Pick up misaligned start bytes (get pointer 4-byte aligned)\r | |
63 | _StartByteZero:\r | |
64 | mov eax, edi \r | |
65 | and al, 3 ; check lower 2 bits of address\r | |
66 | test al, al\r | |
67 | je _ZeroBlocks ; already aligned?\r | |
68 | cmp ecx, 0\r | |
69 | je _ZeroMemDone\r | |
70 | \r | |
71 | ; Clear the byte memory location\r | |
72 | mov BYTE PTR [edi], 0 \r | |
73 | inc edi\r | |
74 | \r | |
75 | ; Decrement our count\r | |
76 | dec ecx\r | |
77 | jmp _StartByteZero ; back to top of loop\r | |
78 | \r | |
79 | _ZeroBlocks:\r | |
80 | \r | |
81 | ; Compute how many 64-byte blocks we can clear \r | |
82 | mov edx, ecx\r | |
83 | shr ecx, 6 ; convert to 64-byte count\r | |
84 | shl ecx, 6 ; convert back to bytes\r | |
85 | sub edx, ecx ; subtract from the original count\r | |
86 | shr ecx, 6 ; and this is how many 64-byte blocks\r | |
87 | \r | |
88 | ; If no 64-byte blocks, then skip \r | |
89 | cmp ecx, 0\r | |
90 | je _ZeroRemaining\r | |
91 | \r | |
92 | ; Save mm0\r | |
93 | movq [ebp - 8], mm0 ; Save mm0 to MmxSave\r | |
94 | \r | |
95 | pxor mm0, mm0 ; Clear mm0\r | |
96 | \r | |
97 | _B:\r | |
98 | movq QWORD PTR ds:[edi], mm0\r | |
99 | movq QWORD PTR ds:[edi+8], mm0\r | |
100 | movq QWORD PTR ds:[edi+16], mm0\r | |
101 | movq QWORD PTR ds:[edi+24], mm0\r | |
102 | movq QWORD PTR ds:[edi+32], mm0\r | |
103 | movq QWORD PTR ds:[edi+40], mm0\r | |
104 | movq QWORD PTR ds:[edi+48], mm0\r | |
105 | movq QWORD PTR ds:[edi+56], mm0\r | |
106 | \r | |
107 | add edi, 64\r | |
108 | dec ecx\r | |
109 | jnz _B\r | |
110 | \r | |
111 | ; Restore mm0\r | |
112 | movq mm0, [ebp - 8] ; Restore mm0 from MmxSave\r | |
113 | emms ; Exit MMX Instruction\r | |
114 | \r | |
115 | _ZeroRemaining:\r | |
116 | ; Zero out as many DWORDS as possible\r | |
117 | mov ecx, edx\r | |
118 | shr ecx, 2\r | |
119 | xor eax, eax\r | |
120 | \r | |
121 | rep stosd\r | |
122 | \r | |
123 | ; Zero out remaining as bytes\r | |
124 | mov ecx, edx\r | |
125 | and ecx, 03\r | |
126 | \r | |
127 | rep stosb\r | |
128 | \r | |
129 | _ZeroMemDone:\r | |
130 | \r | |
131 | pop edi\r | |
132 | leave\r | |
133 | ret\r | |
134 | EfiCommonLibZeroMem ENDP \r | |
135 | END\r |