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Rev 5363 Rev 8037
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;; Copyright (C) KolibriOS team 2013-2015. All rights reserved. ;;
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;; Copyright (C) KolibriOS team 2013-2015. All rights reserved. ;;
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;; Distributed under terms of the GNU General Public License    ;;
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;; Distributed under terms of the GNU General Public License    ;;
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;;                                                              ;;
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;;                                                              ;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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$Revision: 5363 $
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$Revision: 8037 $
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; Memory management for USB structures.
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; Protocol layer uses the common kernel heap malloc/free.
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; Memory management for slab structures.
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; Hardware layer has special requirements:
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; The allocator meets special requirements:
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; * memory blocks should be properly aligned
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; * memory blocks are properly aligned
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; * memory blocks should not cross page boundary
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; * memory blocks do not cross page boundary
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; Hardware layer allocates fixed-size blocks.
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; The allocator manages fixed-size blocks.
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; Thus, the specific allocator is quite easy to write:
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; Thus, the specific allocator works as follows:
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; allocate one page, split into blocks, maintain the single-linked
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; allocate one page, split into blocks, maintain the single-linked
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; list of all free blocks in each page.
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; list of all free blocks in each page.
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; Note: size must be a multiple of required alignment.
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; Note: size must be a multiple of required alignment.
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; Data for one pool: dd pointer to the first page, MUTEX lock.
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; Data for one pool: dd pointer to the first page, MUTEX lock.
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; Allocator for fixed-size blocks: allocate a block.
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; Allocator for fixed-size blocks: allocate a block.
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; [ebx-4] = pointer to the first page, ebx = pointer to MUTEX structure.
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; [ebx-4] = pointer to the first page, ebx = pointer to MUTEX structure.
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proc usb_allocate_common
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proc slab_alloc
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; 2e. Get the pointer to the next free block.
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; 2e. Get the pointer to the next free block.
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        mov     ecx, [eax]
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        mov     ecx, [eax]
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; 2f. Update the pointer to the first free block from eax to ecx.
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; 2f. Update the pointer to the first free block from eax to ecx.
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; Normally [edx-8] still contains eax, if so, atomically set it to ecx
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; Normally [edx-8] still contains eax, if so, atomically set it to ecx
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; and proceed to 3.
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; and proceed to 3.
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; However, the price of simplicity of usb_free_common (in particular, it
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; However, the price of simplicity of slab_free (in particular, it doesn't take
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; doesn't take the lock) is that [edx-8] could (rarely) be changed while
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; the lock) is that [edx-8] could (rarely) be changed while we processed steps
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; we processed steps 2d+2e. If so, return to 2d and retry.
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; 2d+2e. If so, return to 2d and retry.
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        lock cmpxchg [edx-8], ecx
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        lock cmpxchg [edx-8], ecx
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        jnz     @b
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        jnz     @b
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.return:
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.return:
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; 3. Release the lock taken in step 1 and return.
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; 3. Release the lock taken in step 1 and return.
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        push    eax
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        push    eax
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        sub     ecx, [.size]
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        sub     ecx, [.size]
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        and     dword [ecx], 0
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        and     dword [ecx], 0
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; 8. Return (start of page).
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; 8. Return (start of page).
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        jmp     .return
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        jmp     .return
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.nomemory:
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.nomemory:
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        dbgstr 'no memory for USB descriptor'
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        dbgstr 'no memory for slab allocation'
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        xor     eax, eax
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        xor     eax, eax
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        jmp     .return
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        jmp     .return
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endp
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endp
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; Allocator for fixed-size blocks: free a block.
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; Allocator for fixed-size blocks: free a block.
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proc usb_free_common
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proc slab_free
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        push    ecx edx
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        push    ecx edx
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virtual at esp
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virtual at esp
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        rd      2       ; saved registers
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        rd      2       ; saved registers
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        dd      ?       ; return address
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        dd      ?       ; return address
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        lock cmpxchg [edx+1-8], ecx
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        lock cmpxchg [edx+1-8], ecx
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        jnz     @b
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        jnz     @b
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        pop     edx ecx
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        pop     edx ecx
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        ret     4
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        ret     4
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endp
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endp
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; Helper procedure: translate physical address in ecx
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; of some transfer descriptor to linear address.
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; in: eax = address of first page
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proc usb_td_to_virt
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; Traverse all pages used for transfer descriptors, looking for the one
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; with physical address as in ecx.
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@@:
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        test    eax, eax
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        jz      .zero
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        push    eax
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        call    get_pg_addr
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        sub     eax, ecx
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        jz      .found
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        cmp     eax, -0x1000
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        ja      .found
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        pop     eax
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        mov     eax, [eax+0x1000-4]
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        jmp     @b
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.found:
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; When found, combine page address from eax with page offset from ecx.
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        pop     eax
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        and     ecx, 0xFFF
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        add     eax, ecx
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.zero:
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        ret
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endp
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