Elaina Claus
8301fc20a8
files that actually include code should be in .nasm files defines/macros/non-code should be in .inc files
166 lines
6.6 KiB
NASM
166 lines
6.6 KiB
NASM
; Copyright (c) 2024 Elaina Claus
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;
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; Permission is hereby granted, free of charge, to any person obtaining a copy
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; of this software and associated documentation files (the "Software"), to deal
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; in the Software without restriction, including without limitation the rights
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; to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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; copies of the Software, and to permit persons to whom the Software is
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; furnished to do so, subject to the following conditions:
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;
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; The above copyright notice and this permission notice shall be included in all
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; copies or substantial portions of the Software.
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;
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; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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; IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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; FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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; AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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; LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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; SOFTWARE.
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%ifndef __INC_E820MEMORY_MAP
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; Address Range Descriptor Structure
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;
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; Offset in Bytes Name Description
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; 0 BaseAddrLow Low 32 Bits of Base Address
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; 4 BaseAddrHigh High 32 Bits of Base Address
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; 8 LengthLow Low 32 Bits of Length in Bytes
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; 12 LengthHigh High 32 Bits of Length in Bytes
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; 16 Type Address type of this range.
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; Address Range Descriptor Structure
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;
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; Offset in Bytes Name Description
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; 0 BaseAddrLow Low 32 Bits of Base Address
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; 4 BaseAddrHigh High 32 Bits of Base Address
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; 8 LengthLow Low 32 Bits of Length in Bytes
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; 12 LengthHigh High 32 Bits of Length in Bytes
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; 16 Type Address type of this range.
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; Input:
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;
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; EAX Function Code E820h
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; EBX Continuation Contains the "continuation value" to get the
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; next run of physical memory. This is the
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; value returned by a previous call to this
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; routine. If this is the first call, EBX
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; must contain zero.
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; ES:DI Buffer Pointer Pointer to an Address Range Descriptor
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; structure which the BIOS is to fill in.
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; ECX Buffer Size The length in bytes of the structure passed
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; to the BIOS. The BIOS will fill in at most
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; ECX bytes of the structure or however much
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; of the structure the BIOS implements. The
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; minimum size which must be supported by both
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; the BIOS and the caller is 20 bytes. Future
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; implementations may extend this structure.
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; EDX Signature 'SMAP' - Used by the BIOS to verify the
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; caller is requesting the system map
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; information to be returned in ES:DI.
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;
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; Output:
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;
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; CF Carry Flag Non-Carry - indicates no error
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; EAX Signature 'SMAP' - Signature to verify correct BIOS
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; revision.
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; ES:DI Buffer Pointer Returned Address Range Descriptor pointer.
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; Same value as on input.
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; ECX Buffer Size Number of bytes returned by the BIOS in the
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; address range descriptor. The minimum size
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; structure returned by the BIOS is 20 bytes.
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; EBX Continuation Contains the continuation value to get the
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; next address descriptor. The actual
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; significance of the continuation value is up
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; to the discretion of the BIOS. The caller
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; must pass the continuation value unchanged
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; as input to the next iteration of the E820
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; call in order to get the next Address Range
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; Descriptor. A return value of zero means that
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; this is the last descriptor
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;
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; Address Range Descriptor Structure
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;
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; Offset in Bytes Name Description
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; 0 BaseAddrLow Low 32 Bits of Base Address
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; 4 BaseAddrHigh High 32 Bits of Base Address
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; 8 LengthLow Low 32 Bits of Length in Bytes
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; 12 LengthHigh High 32 Bits of Length in Bytes
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; 16 Type Address type of this range.
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;
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; The BaseAddrLow and BaseAddrHigh together are the 64 bit BaseAddress of this range.
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; The BaseAddress is the physical address of the start of the range being specified.
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;
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; The LengthLow and LengthHigh together are the 64 bit Length of this range.
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; The Length is the physical contiguous length in bytes of a range being specified.
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;
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; The Type field describes the usage of the described address range as defined in the table below.
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; Value Pneumonic Description
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; 1 AddressRangeMemory This run is available RAM usable by the operating system.
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; 2 AddressRangeReserved This run of addresses is in use or reserved by the system, and must not be used by the operating system.
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; Other Undefined Undefined - Reserved for future use.
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; Address Range Descriptor Structure
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;
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; Offset in Bytes Name Description
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; 0 BaseAddrLow u32 - Low 32 Bits of Base Address
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; 4 BaseAddrHigh u32 - High 32 Bits of Base Address
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; 8 LengthLow u32 - Low 32 Bits of Length in Bytes
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; 12 LengthHigh u32 - High 32 Bits of Length in Bytes
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; 16 Type u32 - Address type of this range.
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; 20 ExtType u32 - ACPI 3.0 extended type
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struc AddressRangeDescStruct_t
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.BaseAddrLow resd 1
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.BaseAddrHigh resd 1
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.LengthLow resd 1
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.LengthHigh resd 1
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.Type resd 1
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.ExtType resd 1
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endstruc
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ALIGN 4, db 0x90
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GetMemoryMap:
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__CDECL16_ENTRY
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push es ; save segment register
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.func:
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mov dword [SteviaInfo + SteviaInfoStruct_t.MemoryMapEntries], 0
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mov eax, 0xE820 ; select 0xE820 function
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xor ebx, ebx ; Continuation value, 0 for the first call
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mov dx, (BIOSMemoryMap >> 4)
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mov es, dx
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xor di, di ; (BIOSMemoryMap >> 4):0 makes di an index into BIOSMemoryMap
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mov ecx, AddressRangeDescStruct_t_size
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mov edx, 0x534D4150 ; 'SMAP' magic
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.loop_L1:
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int 0x15
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jc GetMemoryMap.error
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cmp eax, 0x534D4150
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jne GetMemoryMap.no_smap_returned
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.no_error:
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inc dword [SteviaInfo + SteviaInfoStruct_t.MemoryMapEntries]
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cmp ecx, 20 ; TODO: maybe this could be handled better than just panicing
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jb GetMemoryMap.nonstandard_e820 ; non-standard entry found
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cmp ebx, 0
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je GetMemoryMap.endp ; 0 in ebx means we have reached the end of memory ranges
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add di, AddressRangeDescStruct_t_size ; increment di to next descriptor
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mov edx, eax ; 'SMAP' to edx
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mov eax, 0xE820 ; select E820 function
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jmp GetMemoryMap.loop_L1
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.error:
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ERROR STAGE2_MM_E820_MISC_ERR
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.nonstandard_e820:
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ERROR STAGE2_MM_E820_NONSTANDARD
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.no_smap_returned:
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ERROR STAGE2_MM_E820_NO_SMAP
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.endp:
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pop es
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__CDECL16_EXIT
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ret
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%endif
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%define __INC_E820MEMORY_MAP |