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source: xtideuniversalbios/trunk/Assembly_Library/Src/Serial/SerialServer.asm @ 376

Last change on this file since 376 was 376, checked in by gregli@…, 12 years ago
WIDE checkin... Added copyright and license information to sorce files, as per the GPL instructions for usage.
File size: 12.3 KB

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1	; Project name : Assembly Library
2	; Description : Serial Server Support
3
4	;
5	; XTIDE Universal BIOS and Associated Tools
6	; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2012 by XTIDE Universal BIOS Team.
7	;
8	; This program is free software; you can redistribute it and/or modify
9	; it under the terms of the GNU General Public License as published by
10	; the Free Software Foundation; either version 2 of the License, or
11	; (at your option) any later version.
12	;
13	; This program is distributed in the hope that it will be useful,
14	; but WITHOUT ANY WARRANTY; without even the implied warranty of
15	; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16	; GNU General Public License for more details.
17	; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
18	;
19
20
21	%include "SerialServer.inc"
22
23	; Section containing code
24	SECTION .text
25
26	;--------------------------------------------------------------------
27	; SerialServer_SendReceive:
28	; Parameters:
29	; DX: Packed I/O port and baud rate
30	; ES:SI: Ptr to buffer (for data transfer commands)
31	; SS:BP: Ptr to SerialServer_Command structure
32	; Returns:
33	; AH: INT 13h Error Code
34	; CX: Number of 512-byte blocks transferred
35	; CF: Cleared if success, Set if error
36	; Corrupts registers:
37	; AL, BX, CX, DX
38	;--------------------------------------------------------------------
39	SerialServer_SendReceive:
40
41	push si
42	push di
43	push bp
44
45	;
46	; Unpack I/O port and baud from DPT
47	; Port to DX for the remainder of the routine (+/- different register offsets)
48	; Baud in CH until UART initialization is complete
49	;
50	mov ch,dh
51	xor dh,dh
52	eSHL_IM dx, 2 ; shift from one byte to two
53
54	mov al,[bp+SerialServer_Command.bSectorCount]
55	mov ah,[bp+SerialServer_Command.bCommand]
56
57	;
58	; Command byte and sector count live at the top of the stack, pop/push are used to access
59	;
60	push ax ; save sector count for return value
61	push ax ; working copy on the top of the stack
62
63	%ifndef EXCLUDE_FROM_XTIDE_UNIVERSAL_BIOS ; DF already cleared in Int13h.asm
64	cld
65	%endif
66
67	;----------------------------------------------------------------------
68	;
69	; Initialize UART
70	;
71	; We do this each time since DOS (at boot) or another program may have
72	; decided to reprogram the UART
73	;
74	mov bl,dl ; setup BL with proper values for read/write loops (BH comes later)
75
76	mov al,83h
77	add dl,Serial_UART_lineControl
78	out dx,al
79
80	mov al,ch
81	mov dl,bl ; divisor low
82	out dx,al
83
84	xor ax,ax
85	inc dx ; divisor high
86	push dx
87	out dx,al
88
89	mov al,047h
90	inc dx ; fifo
91	out dx,al
92
93	mov al,03h
94	inc dx ; linecontrol
95	out dx,al
96
97	mov al,0bh
98	inc dx ; modemcontrol
99	out dx,al
100
101	inc dx ; linestatus (no output now, just setting up BH for later use)
102	mov bh,dl
103
104	pop dx ; base, interrupts disabled
105	xor ax,ax
106	out dx,al
107
108	;----------------------------------------------------------------------
109	;
110	; Send Command
111	;
112	; Sends first six bytes of IDEREGS_AND_INTPACK as the command
113	;
114	push es ; save off real buffer location
115	push si
116
117	mov si,bp ; point to IDEREGS for command dispatch;
118	push ss
119	pop es
120
121	mov di,0ffffh ; initialize checksum for write
122	mov bp,di
123
124	mov cx,4 ; writing 3 words (plus 1)
125
126	cli ; interrupts off...
127
128	call SerialServer_WriteProtocol.entry
129
130	pop di ; restore real buffer location (note change from SI to DI)
131	; Buffer is primarily referenced through ES:DI throughout, since
132	; we need to store (read sector) faster than we read (write sector)
133	pop es
134
135	pop ax ; load command byte (done before call to .nextSector on subsequent iterations)
136	push ax
137
138	%ifndef SERIALSERVER_NO_ZERO_SECTOR_COUNTS
139	test al,al ; if no sectors to be transferred, wait for the ACK checksum on the command
140	jz .zeroSectors
141	%endif
142
143	;
144	; Top of the read/write loop, one iteration per sector
145	;
146	.nextSector:
147	mov si,0ffffh ; initialize checksum for read or write
148	mov bp,si
149
150	mov cx,0101h ; writing 256 words (plus 1)
151
152	shr ah,1 ; command byte, are we doing a write?
153	jnc .readEntry
154
155	xchg si,di ; swap pointer and checksum, will be re-swap'ed in WriteProtocol
156	call SerialServer_WriteProtocol.entry
157
158	.zeroSectors:
159	inc cx ; CX = 1 now (0 out of WriteProtocol)
160	jmp .readEntry
161
162	;----------------------------------------------------------------------
163	;
164	; Timeout
165	;
166	; To save code space, we use the contents of DL to decide which byte in the word to return for reading.
167	;
168	.readTimeout:
169	push ax ; not only does this push preserve AX (which we need), but it also
170	; means the stack has the same number of bytes on it as when we are
171	; sending a packet, important for error cleanup and exit
172	mov ah,1
173	call SerialServer_WaitAndPoll_Read
174	pop ax
175	test dl,1
176	jz .readByte1Ready
177	jmp .readByte2Ready
178
179	;----------------------------------------------------------------------------
180	;
181	; Read Block (without interrupts, used when there is a FIFO, high speed)
182	;
183	; NOTE: This loop is very time sensitive. Literally, another instruction
184	; cannot be inserted into this loop without us falling behind at high
185	; speed (460.8K baud) on a 4.77Mhz 8088, making it hard to receive
186	; a full 512 byte block.
187	;
188	.readLoop:
189	stosw ; store word in caller's data buffer
190
191	add bp, ax ; update Fletcher's checksum
192	adc bp, 0
193	add si, bp
194	adc si, 0
195
196	.readEntry:
197	mov dl,bh
198	in al,dx
199	shr al,1 ; data ready (byte 1)?
200	mov dl,bl ; get ready to read data
201	jnc .readTimeout ; nope not ready, update timeouts
202
203	;
204	; Entry point after initial timeout. We enter here so that the checksum word
205	; is not stored (and is left in AX after the loop is complete).
206	;
207	.readByte1Ready:
208	in al, dx ; read data byte 1
209
210	mov ah, al ; store byte in ah for now
211
212	;
213	; note the placement of this reset of dl to bh, and that it is
214	; before the return, which is assymetric with where this is done
215	; above for byte 1. The value of dl is used by the timeout routine
216	; to know which byte to return to (.read_byte1_ready or
217	; .read_byte2_ready)
218	;
219	mov dl,bh
220
221	in al,dx
222	shr al,1 ; data ready (byte 2)?
223	jnc .readTimeout
224	.readByte2Ready:
225	mov dl,bl
226	in al, dx ; read data byte 2
227
228	xchg al, ah ; ah was holding byte 1, reverse byte order
229
230	loop .readLoop
231
232	sti ; interrupts back on ASAP, between packets
233
234	;
235	; Compare checksums
236	;
237	xchg ax,bp
238	xor ah,al
239	mov cx,si
240	xor cl,ch
241	mov al,cl
242	cmp ax,bp
243	jnz SerialServer_OutputWithParameters_Error
244
245	pop ax ; sector count and command byte
246	dec al ; decrement sector count
247	push ax ; save
248	jz SerialServer_OutputWithParameters_ReturnCodeInAL
249
250	cli ; interrupts back off for ACK byte to host
251	; (host could start sending data immediately)
252	out dx,al ; ACK with next sector number
253
254	jmp short .nextSector
255
256	;---------------------------------------------------------------------------
257	;
258	; Cleanup, error reporting, and exit
259	;
260
261	;
262	; Used in situations where a call is underway, such as with SerialServer_WaitAndPoll
263	;
264	ALIGN JUMP_ALIGN
265	SerialServer_OutputWithParameters_ErrorAndPop4Words:
266	add sp,8
267	;;; fall-through
268
269	ALIGN JUMP_ALIGN
270	SerialServer_OutputWithParameters_Error:
271	;----------------------------------------------------------------------
272	;
273	; Clear read buffer
274	;
275	; In case there are extra characters or an error in the FIFO, clear it out.
276	; In theory the initialization of the UART registers above should have
277	; taken care of this, but I have seen cases where this is not true.
278	;
279	xor cx,cx ; timeout this clearing routine, in case the UART isn't there
280	.clearBuffer:
281	mov dl,bh
282	in al,dx
283	mov dl,bl
284	test al,08fh
285	jz .clearBufferComplete
286	test al,1
287	in al,dx
288	loopnz .clearBuffer ; note ZF from test above
289
290	.clearBufferComplete:
291	mov al, 3 ; error return code and CF (low order bit)
292
293	ALIGN JUMP_ALIGN
294	SerialServer_OutputWithParameters_ReturnCodeInAL:
295	%if 0
296	sti ; all paths here will already have interrupts turned back on
297	%endif
298	mov ah, al ; for success, AL will already be zero
299
300	pop bx ; recover "ax" (command and count) from stack
301	pop cx ; recover saved sector count
302	xor ch, ch
303	sub cl, bl ; subtract off the number of sectors that remained
304
305	pop bp
306	pop di
307	pop si
308
309	shr ah, 1 ; shift down return code and CF
310
311	ret
312
313	;--------------------------------------------------------------------
314	; SerialServer_WriteProtocol
315	;
316	; NOTE: As with its read counterpart, this loop is very time sensitive.
317	; Although it will still function, adding additional instructions will
318	; impact the write throughput, especially on slower machines.
319	;
320	; Parameters:
321	; ES:SI: Ptr to buffer
322	; CX: Words to write, plus 1
323	; BP/DI: Initialized for Checksum (-1 in each)
324	; DH: I/O Port high byte
325	; BX: LineStatus Register address (BH) and Receive/Transmit Register address (BL)
326	; Returns:
327	; BP/SI: Checksum for written bytes, compared against ACK from server in .readLoop
328	; CX: Zero
329	; DL: Receive/Transmit Register address
330	; ES:DI: Ptr to buffer
331	; Corrupts registers:
332	; AX
333	;--------------------------------------------------------------------
334	ALIGN JUMP_ALIGN
335	SerialServer_WriteProtocol:
336	.writeLoop:
337	es lodsw ; fetch next word
338
339	out dx,al ; output first byte
340
341	add bp,ax ; update checksum
342	adc bp,0
343	add di,bp
344	adc di,0
345
346	mov dl,bh ; transmit buffer empty?
347	in al,dx
348	test al,20h
349	jz .writeTimeout2 ; nope, use our polling routine
350
351	.writeByte2Ready:
352	mov dl,bl
353	mov al,ah ; output second byte
354	out dx,al
355
356	.entry:
357	mov dl,bh ; transmit buffer empty?
358	in al,dx
359	test al,20h
360	mov dl,bl
361	jz .writeTimeout1 ; nope, use our polling routine
362
363	.writeByte1Ready:
364	loop .writeLoop
365
366	mov ax,di ; fold Fletcher's checksum and output
367	xor al,ah
368	out dx,al ; byte 1
369
370	call SerialServer_WaitAndPoll_Write
371
372	mov ax,bp
373	xor al,ah
374	out dx,al ; byte 2
375
376	xchg si,di ; preserve checksum word in si, move pointer back to di
377
378	ret
379
380	.writeTimeout2:
381	mov dl,ah ; need to preserve AH, but don't need DL (will be reset upon return)
382	call SerialServer_WaitAndPoll_Write
383	mov ah,dl
384	jmp .writeByte2Ready
385
386	.writeTimeout1:
387	ePUSH_T ax, .writeByte1Ready ; return address for ret at end of SC_writeTimeout2
388	;;; fall-through
389
390	;--------------------------------------------------------------------
391	; SerialServer_WaitAndPoll
392	;
393	; Parameters:
394	; AH: UART_LineStatus bit to test (20h for write, or 1h for read)
395	; One entry point fills in AH with 20h for write
396	; DX: Port address (OK if already incremented to UART_lineStatus)
397	; BX:
398	; Stack: 2 words on the stack below the command/count word
399	; Returns:
400	; Returns when desired UART_LineStatus bit is cleared
401	; Jumps directly to error exit if timeout elapses (and cleans up stack)
402	; Corrupts registers:
403	; AX
404	;--------------------------------------------------------------------
405
406	SerialServer_WaitAndPoll_SoftDelayTicks EQU 20
407
408	ALIGN JUMP_ALIGN
409	SerialServer_WaitAndPoll_Write:
410	mov ah,20h
411	;;; fall-through
412
413	ALIGN JUMP_ALIGN
414	SerialServer_WaitAndPoll_Read:
415	push cx
416	push dx
417
418	;
419	; We first poll in a tight loop, interrupts off, for the next character to come in/be sent
420	;
421	xor cx,cx
422	.readTimeoutLoop:
423	mov dl,bh
424	in al,dx
425	test al,ah
426	jnz .readTimeoutComplete
427	loop .readTimeoutLoop
428
429	;
430	; If that loop completes, then we assume there is a long delay involved, turn interrupts back on
431	; and wait for a given number of timer ticks to pass.
432	;
433	sti
434	mov cl,SerialServer_WaitAndPoll_SoftDelayTicks
435	%ifndef SERIALSERVER_TIMER_LOCATION
436	call Timer_InitializeTimeoutWithTicksInCL
437	%else
438	push ax
439	push bx
440	mov ax,SerialServer_WaitAndPoll_SoftDelayTicks
441	mov bx,SERIALSERVER_TIMER_LOCATION
442	call TimerTicks_InitializeTimeoutFromAX
443	pop bx
444	pop ax
445	%endif
446
447	.WaitAndPoll:
448	%ifndef SERIALSERVER_TIMER_LOCATION
449	call Timer_SetCFifTimeout
450	%else
451	push ax
452	push bx
453	mov bx,SERIALSERVER_TIMER_LOCATION
454	call TimerTicks_GetTimeoutTicksLeftToAXfromDSBX
455	pop bx
456	pop ax
457	%endif
458	jc SerialServer_OutputWithParameters_ErrorAndPop4Words
459	in al,dx
460	test al,ah
461	jz .WaitAndPoll
462	cli
463
464	.readTimeoutComplete:
465	pop dx
466	pop cx
467	ret
468
469

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