Rev 4850 | Go to most recent revision | Details | Compare with Previous | Last modification | View Log | RSS feed
Rev | Author | Line No. | Line |
---|---|---|---|
4850 | mario79 | 1 | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; |
2 | ;; ;; |
||
5363 | yogev_ezra | 3 | ;; Copyright (C) KolibriOS team 2013-2015. All rights reserved. ;; |
4850 | mario79 | 4 | ;; Distributed under terms of the GNU General Public License ;; |
5 | ;; ;; |
||
6 | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; |
||
7 | |||
8 | $Revision: 5363 $ |
||
9 | |||
3520 | clevermous | 10 | ; Memory management for USB structures. |
11 | ; Protocol layer uses the common kernel heap malloc/free. |
||
12 | ; Hardware layer has special requirements: |
||
13 | ; * memory blocks should be properly aligned |
||
14 | ; * memory blocks should not cross page boundary |
||
15 | ; Hardware layer allocates fixed-size blocks. |
||
16 | ; Thus, the specific allocator is quite easy to write: |
||
17 | ; allocate one page, split into blocks, maintain the single-linked |
||
18 | ; list of all free blocks in each page. |
||
19 | |||
20 | ; Note: size must be a multiple of required alignment. |
||
21 | |||
22 | ; Data for one pool: dd pointer to the first page, MUTEX lock. |
||
23 | |||
24 | ; Allocator for fixed-size blocks: allocate a block. |
||
25 | ; [ebx-4] = pointer to the first page, ebx = pointer to MUTEX structure. |
||
26 | proc usb_allocate_common |
||
27 | push edi ; save used register to be stdcall |
||
28 | virtual at esp |
||
29 | dd ? ; saved edi |
||
30 | dd ? ; return address |
||
31 | .size dd ? |
||
32 | end virtual |
||
33 | ; 1. Take the lock. |
||
34 | mov ecx, ebx |
||
35 | call mutex_lock |
||
36 | ; 2. Find the first allocated page with a free block, if any. |
||
37 | ; 2a. Initialize for the loop. |
||
38 | mov edx, ebx |
||
39 | .pageloop: |
||
40 | ; 2b. Get the next page, keeping the current in eax. |
||
41 | mov eax, edx |
||
42 | mov edx, [edx-4] |
||
43 | ; 2c. If there is no next page, we're out of luck; go to 4. |
||
44 | test edx, edx |
||
45 | jz .newpage |
||
46 | add edx, 0x1000 |
||
47 | @@: |
||
48 | ; 2d. Get the pointer to the first free block on this page. |
||
49 | ; If there is no free block, continue to 2b. |
||
50 | mov eax, [edx-8] |
||
51 | test eax, eax |
||
52 | jz .pageloop |
||
53 | ; 2e. Get the pointer to the next free block. |
||
54 | mov ecx, [eax] |
||
55 | ; 2f. Update the pointer to the first free block from eax to ecx. |
||
56 | ; Normally [edx-8] still contains eax, if so, atomically set it to ecx |
||
57 | ; and proceed to 3. |
||
58 | ; However, the price of simplicity of usb_free_common (in particular, it |
||
59 | ; doesn't take the lock) is that [edx-8] could (rarely) be changed while |
||
60 | ; we processed steps 2d+2e. If so, return to 2d and retry. |
||
61 | lock cmpxchg [edx-8], ecx |
||
62 | jnz @b |
||
63 | .return: |
||
64 | ; 3. Release the lock taken in step 1 and return. |
||
65 | push eax |
||
66 | mov ecx, ebx |
||
67 | call mutex_unlock |
||
68 | pop eax |
||
69 | pop edi ; restore used register to be stdcall |
||
70 | ret 4 |
||
71 | .newpage: |
||
72 | ; 4. Allocate a new page. |
||
73 | push eax |
||
74 | stdcall kernel_alloc, 0x1000 |
||
75 | pop edx |
||
76 | ; If failed, say something to the debug board and return zero. |
||
77 | test eax, eax |
||
78 | jz .nomemory |
||
79 | ; 5. Add the new page to the tail of list of allocated pages. |
||
80 | mov [edx-4], eax |
||
81 | ; 6. Initialize two service dwords in the end of page: |
||
82 | ; first free block is (start of page) + (block size) |
||
83 | ; (we will return first block at (start of page), so consider it allocated), |
||
84 | ; no next page. |
||
85 | mov edx, eax |
||
86 | lea edi, [eax+0x1000-8] |
||
87 | add edx, [.size] |
||
88 | mov [edi], edx |
||
89 | and dword [edi+4], 0 |
||
90 | ; 7. All blocks starting from edx are free; join them in a single-linked list. |
||
91 | @@: |
||
92 | mov ecx, edx |
||
93 | add edx, [.size] |
||
94 | mov [ecx], edx |
||
95 | cmp edx, edi |
||
96 | jbe @b |
||
97 | sub ecx, [.size] |
||
98 | and dword [ecx], 0 |
||
99 | ; 8. Return (start of page). |
||
100 | jmp .return |
||
101 | .nomemory: |
||
102 | dbgstr 'no memory for USB descriptor' |
||
103 | xor eax, eax |
||
104 | jmp .return |
||
105 | endp |
||
106 | |||
107 | ; Allocator for fixed-size blocks: free a block. |
||
108 | proc usb_free_common |
||
109 | push ecx edx |
||
110 | virtual at esp |
||
111 | rd 2 ; saved registers |
||
112 | dd ? ; return address |
||
113 | .block dd ? |
||
114 | end virtual |
||
115 | ; Insert the given block to the head of free blocks in this page. |
||
116 | mov ecx, [.block] |
||
117 | mov edx, ecx |
||
118 | or edx, 0xFFF |
||
119 | @@: |
||
120 | mov eax, [edx+1-8] |
||
121 | mov [ecx], eax |
||
122 | lock cmpxchg [edx+1-8], ecx |
||
123 | jnz @b |
||
124 | pop edx ecx |
||
125 | ret 4 |
||
126 | endp |
||
127 | |||
4418 | clevermous | 128 | ; Helper procedure: translate physical address in ecx |
3520 | clevermous | 129 | ; of some transfer descriptor to linear address. |
4418 | clevermous | 130 | ; in: eax = address of first page |
3520 | clevermous | 131 | proc usb_td_to_virt |
132 | ; Traverse all pages used for transfer descriptors, looking for the one |
||
133 | ; with physical address as in ecx. |
||
134 | @@: |
||
135 | test eax, eax |
||
136 | jz .zero |
||
137 | push eax |
||
138 | call get_pg_addr |
||
139 | sub eax, ecx |
||
140 | jz .found |
||
141 | cmp eax, -0x1000 |
||
142 | ja .found |
||
143 | pop eax |
||
144 | mov eax, [eax+0x1000-4] |
||
145 | jmp @b |
||
146 | .found: |
||
147 | ; When found, combine page address from eax with page offset from ecx. |
||
148 | pop eax |
||
149 | and ecx, 0xFFF |
||
150 | add eax, ecx |
||
151 | .zero: |
||
152 | ret |
||
153 | endp |