Add memory utilities and math utils
This commit adds the well known primitive memory functions: - Copy Memory - Compare Memory for being equal - Set Memory to a value It also adds a math utility file at the according location.
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GPG Key ID:
1358818BAA38B104
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@ -0,0 +1,52 @@
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; Arguments:
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; [Furthest from EBP]
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; 1. U32 Stepping
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; 0. U32 Affected Value
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; [Nearest to EBP]
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;
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; Returns:
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; - EAX: The next higher multiple of the stepping,
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; as calculated from affected value.
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ceil_to:
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.prolog:
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push esi
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sub esp, 16
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mov esi, esp
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mov [esi + (16 - 4)], ecx
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mov [esi + (16 - 8)], edx
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.check_values:
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mov eax, [ebp - 4]
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cmp eax, 0
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jne .affected_value_is_valid
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xor eax, eax
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jmp .epilog
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.affected_value_is_valid:
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mov ecx, [ebp - 8]
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cmp ecx, 0
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jne .calculate
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xor eax, eax
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jmp .epilog
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.calculate:
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; Calculate how much needs ot be added to the
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; affected value for it to become a multiple of
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; the stepping using the remainder part of the division.
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div ecx
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; EDX now contains how much the affected value
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; 'goes over' the last multiple of the stepping.
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; Now, it can be calculated how much has to be added
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; to the affected value to make it the next multiple
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; of the stepping.
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mov ecx, [ebp - 8]
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sub ecx, edx
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mov eax, [ebp - 4]
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add eax, ecx
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.epilog:
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mov edx, [esi + (16 - 8)]
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mov ecx, [esi + (16 - 4)]
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add esp, 16
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pop esi
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ret
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@ -0,0 +1,152 @@
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mem_copy:
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; todo(perf): Copy multiple bytes at once
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.prolog:
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push esi
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sub esp, 64
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mov esi, esp
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; Save registers
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mov [esi + (64 - 4)], eax
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mov [esi + (64 - 8)], ebx
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mov [esi + (64 - 12)], ecx
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mov [esi + (64 - 16)], edx
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mov [esi + (64 - 20)], edi
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.body:
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mov edx, [ebp - 4] ; Destination
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mov edi, [ebp - 8] ; Source
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xor eax, eax ; Current Byte Offset
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.body.copy_loop:
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mov ebx, edi
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add ebx, eax
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mov cl, [ebx]
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mov ebx, edx
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add ebx, eax
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mov [ebx], cl
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inc eax
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cmp eax, [ebp - 12]
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jb .body.copy_loop
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.epilog:
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; Restore registers
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mov eax, [esi + (64 - 4)]
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mov ebx, [esi + (64 - 8)]
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mov ecx, [esi + (64 - 12)]
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mov edx, [esi + (64 - 16)]
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mov edi, [esi + (64 - 20)]
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add esp, 64
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pop esi
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ret
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; Furthest from EBP
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; 3. Length of block 1 and block 2
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; 2. Block 2
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; 1. Block 1
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; Nearest to EBP
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mem_equal:
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.prolog:
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push esi
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sub esp, 32
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mov esi, esp
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; Save registers
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mov [esi + (32 - 4)], ebx
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mov [esi + (32 - 8)], ecx
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mov [esi + (32 - 12)], edx
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mov [esi + (32 - 16)], edi
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.body:
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mov edx, [ebp - 4] ; Block 1
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mov edi, [ebp - 8] ; Block 2
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xor eax, eax ; Current Byte Offset
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.body.compare_loop:
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mov ebx, edx
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add ebx, eax
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mov dl, [ebx]
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mov ebx, edi
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add ebx, eax
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mov dh, [ebx]
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inc eax
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cmp dl, dh
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je .body.compare_loop.condition
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; On NOT equal
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xor eax, eax
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jmp .epilog
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.body.compare_loop.condition:
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inc eax
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cmp eax, [ebp - 12]
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jb .body.compare_loop
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mov eax, 1
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.epilog:
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; Restore registers
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mov ebx, [esi + (32 - 4)]
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mov ecx, [esi + (32 - 8)]
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mov edx, [esi + (32 - 12)]
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mov edi, [esi + (32 - 16)]
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add esp, 32
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pop esi
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ret
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; ebp - 4: Area Pointer
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; ebp - 8: Length of Area
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; ebp - 12: Byte Value to set
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mem_set:
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.prolog:
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push esi
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sub esp, 64
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mov esi, esp
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; Save registers
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mov [esi + (64 - 4)], eax
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mov [esi + (64 - 8)], ebx
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mov [esi + (64 - 12)], ecx
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mov [esi + (64 - 16)], edx
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mov [esi + (64 - 20)], edi
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.body:
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mov ebx, [ebp - 4]
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mov dl, [ebp - 12]
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; Make EDI the Last Byte Pointer
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mov edi, [ebp - 4]
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add edi, [ebp - 8]
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.body.setter_loop:
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cmp ebx, edi
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jae .epilog
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mov [ebx], dl
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inc ebx
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jb .body.setter_loop
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.epilog:
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; Restore registers
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mov eax, [esi + (64 - 4)]
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mov ebx, [esi + (64 - 8)]
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mov ecx, [esi + (64 - 12)]
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mov edx, [esi + (64 - 16)]
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mov edi, [esi + (64 - 20)]
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add esp, 64
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pop esi
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ret
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