| 1a49e2aa |
1 | ;***\r |
| 2 | ;llmul.asm - long multiply routine\r |
| 3 | ;\r |
| 4 | ; Copyright (c) Microsoft Corporation. All rights reserved.\r |
| 5 | ; SPDX-License-Identifier: BSD-2-Clause-Patent\r |
| 6 | ;\r |
| 7 | ;Purpose:\r |
| 8 | ; Defines long multiply routine\r |
| 9 | ; Both signed and unsigned routines are the same, since multiply's\r |
| 10 | ; work out the same in 2's complement\r |
| 11 | ; creates the following routine:\r |
| 12 | ; __allmul\r |
| 13 | ;\r |
| 14 | ;Original Implemenation: MSVC 14.12.25827\r |
| 15 | ;\r |
| 16 | ;*******************************************************************************\r |
| 17 | .686\r |
| 18 | .model flat,C\r |
| 19 | .code\r |
| 20 | \r |
| 21 | \r |
| 22 | ;***\r |
| 23 | ;llmul - long multiply routine\r |
| 24 | ;\r |
| 25 | ;Purpose:\r |
| 26 | ; Does a long multiply (same for signed/unsigned)\r |
| 27 | ; Parameters are not changed.\r |
| 28 | ;\r |
| 29 | ;Entry:\r |
| 30 | ; Parameters are passed on the stack:\r |
| 31 | ; 1st pushed: multiplier (QWORD)\r |
| 32 | ; 2nd pushed: multiplicand (QWORD)\r |
| 33 | ;\r |
| 34 | ;Exit:\r |
| 35 | ; EDX:EAX - product of multiplier and multiplicand\r |
| 36 | ; NOTE: parameters are removed from the stack\r |
| 37 | ;\r |
| 38 | ;Uses:\r |
| 39 | ; ECX\r |
| 40 | ;\r |
| 41 | ;Exceptions:\r |
| 42 | ;\r |
| 43 | ;*******************************************************************************\r |
| 44 | _allmul PROC NEAR\r |
| 45 | \r |
| 46 | A EQU [esp + 4] ; stack address of a\r |
| 47 | B EQU [esp + 12] ; stack address of b\r |
| 48 | \r |
| 49 | HIGH_PART EQU [4] ;\r |
| 50 | LOW_PART EQU [0]\r |
| 51 | \r |
| 52 | ;\r |
| 53 | ; AHI, BHI : upper 32 bits of A and B\r |
| 54 | ; ALO, BLO : lower 32 bits of A and B\r |
| 55 | ;\r |
| 56 | ; ALO * BLO\r |
| 57 | ; ALO * BHI\r |
| 58 | ; + BLO * AHI\r |
| 59 | ; ---------------------\r |
| 60 | ;\r |
| 61 | \r |
| 62 | mov eax,HIGH_PART(A)\r |
| 63 | mov ecx,HIGH_PART(B)\r |
| 64 | or ecx,eax ;test for both high dwords zero.\r |
| 65 | mov ecx,LOW_PART(B)\r |
| 66 | jnz short hard ;both are zero, just mult ALO and BLO\r |
| 67 | \r |
| 68 | mov eax,LOW_PART(A)\r |
| 69 | mul ecx\r |
| 70 | \r |
| 71 | ret 16 ; callee restores the stack\r |
| 72 | \r |
| 73 | hard:\r |
| 74 | push ebx\r |
| 75 | \r |
| 76 | ; must redefine A and B since esp has been altered\r |
| 77 | \r |
| 78 | A2 EQU [esp + 8] ; stack address of a\r |
| 79 | B2 EQU [esp + 16] ; stack address of b\r |
| 80 | \r |
| 81 | mul ecx ;eax has AHI, ecx has BLO, so AHI * BLO\r |
| 82 | mov ebx,eax ;save result\r |
| 83 | \r |
| 84 | mov eax,LOW_PART(A2)\r |
| 85 | mul dword ptr HIGH_PART(B2) ;ALO * BHI\r |
| 86 | add ebx,eax ;ebx = ((ALO * BHI) + (AHI * BLO))\r |
| 87 | \r |
| 88 | mov eax,LOW_PART(A2);ecx = BLO\r |
| 89 | mul ecx ;so edx:eax = ALO*BLO\r |
| 90 | add edx,ebx ;now edx has all the LO*HI stuff\r |
| 91 | \r |
| 92 | pop ebx\r |
| 93 | \r |
| 94 | ret 16 ; callee restores the stack\r |
| 95 | \r |
| 96 | _allmul ENDP\r |
| 97 | \r |
| 98 | end\r |
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