projects / mirror_edk2.git / blame
| Commit | Line | Data |
|---|---|---|
| 102b4c7c HW |
1 | ;------------------------------------------------------------------------------\r |
| 2 | ;\r | |
| 3 | ; Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>\r | |
| 4 | ; This program and the accompanying materials\r | |
| 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 | ; IsZeroBuffer.nasm\r | |
| 15 | ;\r | |
| 16 | ; Abstract:\r | |
| 17 | ;\r | |
| 18 | ; IsZeroBuffer function\r | |
| 19 | ;\r | |
| 20 | ; Notes:\r | |
| 21 | ;\r | |
| 22 | ;------------------------------------------------------------------------------\r | |
| 23 | \r | |
| 24 | SECTION .text\r | |
| 25 | \r | |
| 26 | ;------------------------------------------------------------------------------\r | |
| 27 | ; BOOLEAN\r | |
| 28 | ; EFIAPI\r | |
| 29 | ; InternalMemIsZeroBuffer (\r | |
| 30 | ; IN CONST VOID *Buffer,\r | |
| 31 | ; IN UINTN Length\r | |
| 32 | ; );\r | |
| 33 | ;------------------------------------------------------------------------------\r | |
| 34 | global ASM_PFX(InternalMemIsZeroBuffer)\r | |
| 35 | ASM_PFX(InternalMemIsZeroBuffer):\r | |
| 36 | push edi\r | |
| 37 | mov edi, [esp + 8] ; edi <- Buffer\r | |
| 38 | mov edx, [esp + 12] ; edx <- Length\r | |
| 39 | xor ecx, ecx ; ecx <- 0\r | |
| 40 | sub ecx, edi\r | |
| 41 | and ecx, 15 ; ecx + edi aligns on 16-byte boundary\r | |
| 42 | jz @Is16BytesZero\r | |
| 43 | cmp ecx, edx\r | |
| 44 | cmova ecx, edx ; bytes before the 16-byte boundary\r | |
| 45 | sub edx, ecx\r | |
| 46 | xor eax, eax ; eax <- 0, also set ZF\r | |
| 47 | repe scasb\r | |
| 48 | jnz @ReturnFalse ; ZF=0 means non-zero element found\r | |
| 49 | @Is16BytesZero:\r | |
| 50 | mov ecx, edx\r | |
| 51 | and edx, 15\r | |
| 52 | shr ecx, 4\r | |
| 53 | jz @IsBytesZero\r | |
| 54 | .0:\r | |
| 55 | pxor xmm0, xmm0 ; xmm0 <- 0\r | |
| 56 | pcmpeqb xmm0, [edi] ; check zero for 16 bytes\r | |
| 57 | pmovmskb eax, xmm0 ; eax <- compare results\r | |
| 58 | cmp eax, 0xffff\r | |
| 59 | jnz @ReturnFalse\r | |
| 60 | add edi, 16\r | |
| 61 | loop .0\r | |
| 62 | @IsBytesZero:\r | |
| 63 | mov ecx, edx\r | |
| 64 | xor eax, eax ; eax <- 0, also set ZF\r | |
| 65 | repe scasb\r | |
| 66 | jnz @ReturnFalse ; ZF=0 means non-zero element found\r | |
| 67 | pop edi\r | |
| 68 | mov eax, 1 ; return TRUE\r | |
| 69 | ret\r | |
| 70 | @ReturnFalse:\r | |
| 71 | pop edi\r | |
| 72 | xor eax, eax\r | |
| 73 | ret ; return FALSE\r | |
| 74 | \r |