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sb16_buffer_allocated db 0

endg

; Allocates [.size] bytes so that the target memory block

; is inside one 64K page for 24-bit DMA controller,

; that is, somewhere between 00xx0000h and 00xxFFFFh.

proc alloc_dma24

; Implementation note.

; The only user of that function is SB16 driver,

; so just return a statically allocated buffer.

virtual at esp

                dd      ? ; return address

.size           dd      ?

end virtual

        cmp     [sb16_buffer_allocated], 0

        jnz     .fail

        inc     [sb16_buffer_allocated]

        mov     eax, SB16Buffer

        ret     4

.fail:

        xor     eax, eax

        ret     4

endp

; Allocates a physical page for master page table

; that duplicates first Mb of OS_BASE at address 0;

; used for starting APs and for shutting down,

; where it is important to execute code in trivial-mapped pages.

; Returns eax = allocated physical page.

proc create_trampoline_pgmap

; The only non-trivial moment:

; we need a linear address to fill information,

; but we don't need it outside of this function,

; so we're returning physical address.

; Therefore, allocate memory with kernel_alloc,

; this will allocate physical page and a linear address somewhere,

; and deallocate only linear address with free_kernel_space.

        stdcall kernel_alloc, 0x1000

        mov     edi, eax

        mov     esi, master_tab

        mov     ecx, 1024

        rep movsd

        mov     ecx, [master_tab+(OS_BASE shr 20)]

        mov     [eax], ecx

        mov     edi, eax

        call    get_pg_addr

        push    eax

        stdcall free_kernel_space, edi

        pop     eax

        ret

endp