Diff of /trunk/mkinitrd-magellan/isolinux/getc.inc

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	revision 1132 by niro, Sat Sep 1 22:45:15 2007 UTC	revision 1133 by niro, Thu Aug 19 09:50:43 2010 UTC
#	Line 1	Line 1
	;; $Id: getc.inc,v 1.1 2007-09-01 22:44:04 niro Exp $
1	;; -----------------------------------------------------------------------	;; -----------------------------------------------------------------------
2	;;	;;
3	;;   Copyright 1994-2002 H. Peter Anvin - All Rights Reserved	;;   Copyright 1994-2009 H. Peter Anvin - All Rights Reserved
4		;;   Copyright 2009 Intel Corporation; author: H. Peter Anvin
5	;;	;;
6	;;   This program is free software; you can redistribute it and/or modify	;;   This program is free software; you can redistribute it and/or modify
7	;;   it under the terms of the GNU General Public License as published by	;;   it under the terms of the GNU General Public License as published by
#	Line 16	Line 16
16	;;	;;
17	;; Simple file handling library (open, getc, ungetc)	;; Simple file handling library (open, getc, ungetc)
18	;;	;;
19		;; WARNING: This interface uses the real_mode_seg/comboot_seg.
20		;;
21
22		MAX_GETC_LG2 equ 4 ; Max number of file nesting
23		MAX_GETC equ (1 << MAX_GETC_LG2)
24		bytes_per_getc_lg2 equ 16-MAX_GETC_LG2
25		bytes_per_getc equ (1 << bytes_per_getc_lg2)
26		secs_per_getc equ bytes_per_getc/SECTOR_SIZE
27		MAX_UNGET equ 9 ; Max bytes that can be pushed back
28
29		struc getc_file
30		gc_file resw 1 ; File pointer
31		gc_bufbytes resw 1 ; Bytes left in buffer
32		gc_bufdata resw 1 ; Pointer to data in buffer
33		gc_unget_cnt resb 1 ; Character pushed back count
34		gc_unget_buf resb MAX_UNGET ; Character pushed back buffer
35		endstruc
36		getc_file_lg2 equ 4 ; Size of getc_file as a power of 2
37
38		%ifndef DEPEND
39		%if (getc_file_size != (1 << getc_file_lg2))
40		%error "getc_file_size != (1 << getc_file_lg2)"
41		%endif
42		%endif
43
44	;	;
45	; open,getc: Load a file a character at a time for parsing in a manner	; open,getc: Load a file a character at a time for parsing in a manner
46	; similar to the C library getc routine. Only one simultaneous	; similar to the C library getc routine.
47	; use is supported.  Note: "open" trashes the trackbuf.	; Up to MAX_GETC files can be open at the same time,
48		; they are accessed in a stack-like fashion.
49		;
50		; All routines assume CS == DS.
51	;	;
52	; open: Input: mangled filename in DS:DI	; open: Input: mangled filename in DS:DI
53	; Output: ZF set on file not found or zero length	; Output: ZF set on file not found or zero length
54	;	;
55	; openfd: Input: file handle in SI	; openfd: Input: file handle in SI, file size in EAX
56	; Output: none	; Output: ZF set on getc stack overflow
57	;	;
58	; getc: Output: CF set on end of file	; getc: Output: CF set on end of file
59	; Character loaded in AL	; Character loaded in AL
60	;	;
61		; close: Output: CF set if nothing open
62		;
63	open:	open:
64	call searchdir	call searchdir
65	jz openfd.ret	jz openfd.ret
66	openfd:	openfd:
67	pushf	push bx
68	mov [FBytes],ax
69	mov [FBytes+2],dx	mov bx,[CurrentGetC]
70	mov eax,[FBytes]	sub bx,getc_file_size
71	add eax,SECTOR_SIZE-1	cmp bx,GetCStack
72	shr eax,SECTOR_SHIFT	jb .stack_full ; Excessive nesting
73	mov [FSectors],eax ; Number of sectors	mov [CurrentGetC],bx
74	mov [FNextClust],si ; Cluster pointer
75	mov ax,[EndOfGetCBuf] ; Pointer at end of buffer ->	mov [bx+gc_file],si ; File pointer
76	mov [FPtr],ax ;  nothing loaded yet	xor ax,ax
77	popf ; Restore no ZF	mov [bx+gc_bufbytes],ax ; Buffer empty
78		mov [bx+gc_unget_cnt],al ; ungetc buffer empty
79
80		inc ax ; ZF <- 0
81		pop bx
82	.ret: ret	.ret: ret
83
84		.stack_full:
85		call close_file
86		xor ax,ax ; ZF <- 1
87		pop bx
88		ret
89
90	getc:	getc:
91	stc ; If we exit here -> EOF	push bx
92	mov ecx,[FBytes]	push si
93	jecxz .ret	push di
94	mov si,[FPtr]	push es
95	cmp si,[EndOfGetCBuf]
96	jb .loaded	mov di,[CurrentGetC]
97	; Buffer empty -- load another set	movzx bx,byte [di+gc_unget_cnt]
98	mov ecx,[FSectors]	and bx,bx
99	cmp ecx,trackbufsize >> SECTOR_SHIFT	jnz .have_unget
100	jna .oksize
101	mov ecx,trackbufsize >> SECTOR_SHIFT	mov si,real_mode_seg ; Borrow the real_mode_seg
102	.oksize: sub [FSectors],ecx ; Reduce remaining clusters	mov es,si
103	mov si,[FNextClust]
104	push es ; ES may be != DS, save old ES	.got_data:
105	push ds	sub word [di+gc_bufbytes],1
106		jc .get_data ; Was it zero already?
107		mov si,[di+gc_bufdata]
108		mov al,[es:si]
109		inc si
110		mov [di+gc_bufdata],si
111		.done:
112		clc
113		.ret:
114	pop es	pop es
115	mov bx,getcbuf	pop di
116		pop si
117		pop bx
118		ret
119		.have_unget:
120		dec bx
121		mov al,[di+bx+gc_unget_buf]
122		mov [di+gc_unget_cnt],bl
123		jmp .done
124
125		.get_data:
126		pushad
127		; Compute start of buffer
128		mov bx,di
129		sub bx,GetCStack
130		shl bx,bytes_per_getc_lg2-getc_file_lg2
131
132		mov [di+gc_bufdata],bx
133		mov si,[di+gc_file]
134		and si,si
135		mov [di+gc_bufbytes],si ; In case SI == 0
136		jz .empty
137		mov cx,bytes_per_getc >> SECTOR_SHIFT
138		call getfssec
139		mov [di+gc_bufbytes],cx
140		mov [di+gc_file],si
141		jcxz .empty
142		popad
143		TRACER 'd'
144		jmp .got_data
145
146		.empty:
147		TRACER 'e'
148		; [di+gc_bufbytes] is zero already, thus we will continue
149		; to get EOF on any further attempts to read the file.
150		popad
151		xor al,al ; Return a predictable zero
152		stc
153		jmp .ret
154
155		;
156		; This is similar to getc, except that we read up to CX bytes and
157		; store them in ES:DI.  Eventually this could get optimized...
158		;
159		; On return, CX and DI are adjusted by the number of bytes actually read.
160		;
161		readc:
162		push ax
163		.loop:
164		call getc
165		jc .out
166		stosb
167		loop .loop
168		.out:
169		pop ax
170		ret
171
172		;
173		; close: close the top of the getc stack
174		;
175		close:
176	push bx	push bx
177	call getfssec ; Load a trackbuf full of data	push si
178	mov [FNextClust],si ; Store new next pointer	mov bx,[CurrentGetC]
179	pop si ; SI -> newly loaded data	mov si,[bx+gc_file]
180	pop es ; Restore ES	call close_file
181	.loaded: lodsb ; Load a byte, increment SI	add bx,getc_file_size
182	mov [FPtr],si ; Update next byte pointer	mov [CurrentGetC],bx
183	dec dword [FBytes] ; Update bytes left counter	pop si
184	clc ; Not EOF	pop bx
185	.ret: ret	ret
186
187	;	;
188	; ungetc: Push a character (in AL) back into the getc buffer	; ungetc: Push a character (in AL) back into the getc buffer
189	; Note: if more than one byte is pushed back, this may cause	; Note: if more than MAX_UNGET bytes are pushed back, all
190	; bytes to be written below the getc buffer boundary.  If there	; hell will break loose.
	; is a risk for this to occur, the getcbuf base address should
	; be moved up.
191	;	;
192	ungetc:	ungetc:
193	mov si,[FPtr]	push di
194	dec si	push bx
195	mov [si],al	mov di,[CurrentGetC]
196	mov [FPtr],si	movzx bx,[di+gc_unget_cnt]
197	inc dword [FBytes]	mov [bx+di+gc_unget_buf],al
198		inc bx
199		mov [di+gc_unget_cnt],bl
200		pop bx
201		pop di
202	ret	ret
203
204	;	;
#	Line 134  getint:	Line 243  getint:
243	.loaded: mov byte [di],0	.loaded: mov byte [di],0
244	mov si,NumBuf	mov si,NumBuf
245	; Fall through to parseint	; Fall through to parseint
246	;	;
247	; parseint: Convert an integer to a number in EBX	; parseint: Convert an integer to a number in EBX
248	; Get characters from string in DS:SI	; Get characters from string in DS:SI
249	; Return CF on error	; Return CF on error
250	; DS:SI points to first character after number	; DS:SI points to first character after number
251	;	;
252	;               Syntaxes accepted: [-]dec, [-]0+oct, [-]0x+hex, val+K, val+M	;               Syntaxes accepted: [-]dec, [-]0+oct, [-]0x+hex, val+[KMG]
253	;	;
254	parseint:	parseint:
255	push eax	push eax
#	Line 182  parseint:	Line 290  parseint:
290	call unhexchar	call unhexchar
291	jc .km                ; Not a (hex) digit	jc .km                ; Not a (hex) digit
292	cmp al,cl	cmp al,cl
293	jae .km ; Invalid for base	jae .km ; Invalid for base
294	imul ebx,ecx ; Multiply accumulated by base	imul ebx,ecx ; Multiply accumulated by base
295	add ebx,eax             ; Add current digit	add ebx,eax             ; Add current digit
296	lodsb	lodsb
#	Line 195  parseint:	Line 303  parseint:
303	je .isk	je .isk
304	cmp al,'m'	cmp al,'m'
305	je .ism	je .ism
306		cmp al,'g'
307		je .isg
308	dec si ; Back up	dec si ; Back up
309	.fini: and bp,bp	.fini: and bp,bp
310	jz .ret ; CF=0!	jz .ret ; CF=0!
#	Line 206  parseint:	Line 316  parseint:
316	ret	ret
317	.err: stc	.err: stc
318	jmp short .ret	jmp short .ret
319	.isk: shl ebx,10 ; x 2^10	.isg: shl ebx,10 ; * 2^30
320	jmp short .done	.ism: shl ebx,10 ; * 2^20
321	.ism: shl ebx,20 ; x 2^20	.isk: shl ebx,10 ; * 2^10
322	jmp short .done	jmp .fini
323
324		section .bss1
	section .bss
325	alignb 4	alignb 4
326	NumBuf resb 15 ; Buffer to load number	NumBuf resb 15 ; Buffer to load number
327	NumBufEnd resb 1 ; Last byte in NumBuf	NumBufEnd resb 1 ; Last byte in NumBuf
328	FBytes resd 1 ; Number of bytes left in getc file
329	FSectors resd 1 ; Number of sectors in getc file	GetCStack resb getc_file_size*MAX_GETC
330	FNextClust resw 1 ; Pointer to next cluster in d:o	.end equ $
331	FPtr resw 1 ; Pointer to next char in buffer
332		section .data
333		CurrentGetC dw GetCStack.end ; GetCStack empty
334
335	;	;
336	; unhexchar:    Convert a hexadecimal digit in AL to the equivalent number;	; unhexchar:    Convert a hexadecimal digit in AL to the equivalent number;
#	Line 240  unhexchar:	Line 351  unhexchar:
351	ja .err	ja .err
352	sub al,'a'-10           ; CF <- 0	sub al,'a'-10           ; CF <- 0
353	ret	ret
354	.err:         stc	.err: stc
355	.ret: ret	.ret: ret
356
357	;	;
#	Line 288  getline:	Line 399  getline:
399	stosb	stosb
400	.xret: popf	.xret: popf
401	ret	ret
402
403		;
404		; parseint_esdi:
405		; Same as parseint, but takes the input in ES:DI
406		;
407		parseint_esdi:
408		push ds
409		push es
410		pop ds
411		xchg si,di
412		call parseint
413		xchg si,di
414		pop ds
415		ret

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