mkinitrd-magellan/isolinux/rllpack.inc

; -*- fundamental -*- ---------------------------------------------------
;
;   Copyright 2007-2009 H. Peter Anvin - All Rights Reserved
;   Copyright 2009 Intel Corporation; author: H. Peter Anvin
;
;   This program is free software; you can redistribute it and/or modify
;   it under the terms of the GNU General Public License as published by
;   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
;   Boston MA 02111-1307, USA; either version 2 of the License, or
;   (at your option) any later version; incorporated herein by reference.
;
; -----------------------------------------------------------------------

;
; rllpack.inc
;
; Very simple RLL compressor/decompressor, used to pack binary structures
; together.
;
; Format of leading byte
; 1-128		= x verbatim bytes follow
; 129-223	= (x-126) times subsequent byte
; 224-255	= (x-224)*256+(next byte) times the following byte
; 0		= end of data
;
; These structures are stored *in reverse order* in high memory.
; High memory pointers point to one byte beyond the end.
;

		section .text

;
; rllpack:
;	Pack ECX bytes from ESI into EDI.
;	Returns updated ESI and EDI.
;
rllpack:
		push word .pmentry
		call simple_pm_call
		ret

		bits 32
.pmentry:
		push ecx
		push ebx
		push edx
.startseq:
		xor eax,eax		; Zero byte
		xor ebx,ebx		; Run length zero
		dec edi
		mov edx,edi		; Pointer to header byte
		mov [edi],al		; Create header byte
		jcxz .done		; If done, this was the terminator
.stdbyte:
		lodsb
		dec edi
		mov [edi],al
		dec ecx
		cmp ah,al
		je .same
.diff:
		mov ah,al
		xor ebx,ebx
.plainbyte:
		inc ebx
		inc byte [edx]
		jcxz .startseq
		jns .stdbyte
		jmp .startseq
.same:
		cmp bl,2
		jb .plainbyte
		; 3 bytes or more in a row, time to convert sequence
		sub [edx],bl
		jnz .normal
		inc edi			; We killed a whole stretch,
					; drop start byte
.normal:
		inc ebx
		add edi,ebx		; Remove the stored run bytes
.getrun:
		jcxz .nomatch
		lodsb
		cmp al,ah
		jne .nomatch
		cmp bx,(256-224)*256-1	; Maximum run size
		jae .nomatch
		inc ebx
		dec ecx
		jmp .getrun
.nomatch:
		cmp bx,224-126
		jae .twobyte
.onebyte:
		add bl,126
		dec edi
		mov [edi],bl
		jmp .storebyte
.twobyte:
		add bh,224
		sub edi,2
		mov [edi],bx
.storebyte:
		dec edi
		mov [edi],ah
		dec esi			; Reload subsequent byte
		jmp .startseq
.done:
		pop edx
		pop ebx
		pop ecx
		ret

		bits 16
;
; rllunpack:
;	Unpack bytes from ESI into EDI
;	On return ESI, EDI are updated and
;	ECX contains number of bytes output.
;
rllunpack:
		push word .pmentry
		call simple_pm_call
		ret

		bits 32
.pmentry:
		push edi
		xor ecx,ecx
.header:
		dec esi
		mov cl,[esi]
		jcxz .done
		cmp cl,129
		jae .isrun
		; Not a run
.copy:
		dec esi
		mov al,[esi]
		stosb
		loop .copy
		jmp .header
.isrun:
		cmp cl,224
		jae .longrun
		sub cl,126
.dorun:
		dec esi
		mov al,[esi]
		rep stosb
		jmp .header
.longrun:
		sub cl,224
		mov ch,cl
		dec esi
		mov cl,[esi]
		jmp .dorun
.done:
		pop ecx
		sub ecx,edi
		neg ecx
		ret

		bits 16
1	niro	1133	; -- fundamental -- ---------------------------------------------------
2	niro	532	;
3	niro	1133	; Copyright 2007-2009 H. Peter Anvin - All Rights Reserved
4			; Copyright 2009 Intel Corporation; author: H. Peter Anvin
5			;
6	niro	532	; 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
8			; the Free Software Foundation, Inc., 53 Temple Place Ste 330,
9			; Boston MA 02111-1307, USA; either version 2 of the License, or
10			; (at your option) any later version; incorporated herein by reference.
11			;
12			; -----------------------------------------------------------------------
13
14			;
15			; rllpack.inc
16			;
17			; Very simple RLL compressor/decompressor, used to pack binary structures
18			; together.
19			;
20			; Format of leading byte
21			; 1-128 = x verbatim bytes follow
22	niro	1133	; 129-223 = (x-126) times subsequent byte
23			; 224-255 = (x-224)*256+(next byte) times the following byte
24	niro	532	; 0 = end of data
25			;
26	niro	1133	; These structures are stored in reverse order in high memory.
27			; High memory pointers point to one byte beyond the end.
28			;
29	niro	532
30			section .text
31
32			;
33			; rllpack:
34	niro	1133	; Pack ECX bytes from ESI into EDI.
35			; Returns updated ESI and EDI.
36	niro	532	;
37			rllpack:
38	niro	1133	push word .pmentry
39			call simple_pm_call
40			ret
41
42			bits 32
43			.pmentry:
44			push ecx
45			push ebx
46			push edx
47	niro	532	.startseq:
48	niro	1133	xor eax,eax ; Zero byte
49			xor ebx,ebx ; Run length zero
50			dec edi
51			mov edx,edi ; Pointer to header byte
52			mov [edi],al ; Create header byte
53			jcxz .done ; If done, this was the terminator
54	niro	532	.stdbyte:
55			lodsb
56	niro	1133	dec edi
57			mov [edi],al
58			dec ecx
59	niro	532	cmp ah,al
60			je .same
61			.diff:
62			mov ah,al
63	niro	1133	xor ebx,ebx
64	niro	532	.plainbyte:
65	niro	1133	inc ebx
66			inc byte [edx]
67			jcxz .startseq
68	niro	532	jns .stdbyte
69			jmp .startseq
70			.same:
71			cmp bl,2
72			jb .plainbyte
73			; 3 bytes or more in a row, time to convert sequence
74	niro	1133	sub [edx],bl
75	niro	532	jnz .normal
76	niro	1133	inc edi ; We killed a whole stretch,
77			; drop start byte
78	niro	532	.normal:
79	niro	1133	inc ebx
80			add edi,ebx ; Remove the stored run bytes
81	niro	532	.getrun:
82	niro	1133	jcxz .nomatch
83	niro	532	lodsb
84			cmp al,ah
85			jne .nomatch
86	niro	1133	cmp bx,(256-224)*256-1 ; Maximum run size
87			jae .nomatch
88			inc ebx
89			dec ecx
90	niro	532	jmp .getrun
91			.nomatch:
92	niro	1133	cmp bx,224-126
93			jae .twobyte
94			.onebyte:
95			add bl,126
96			dec edi
97			mov [edi],bl
98			jmp .storebyte
99			.twobyte:
100			add bh,224
101			sub edi,2
102			mov [edi],bx
103			.storebyte:
104			dec edi
105			mov [edi],ah
106			dec esi ; Reload subsequent byte
107	niro	532	jmp .startseq
108			.done:
109	niro	1133	pop edx
110			pop ebx
111			pop ecx
112	niro	532	ret
113	niro	1133
114			bits 16
115	niro	532	;
116			; rllunpack:
117	niro	1133	; Unpack bytes from ESI into EDI
118			; On return ESI, EDI are updated and
119			; ECX contains number of bytes output.
120			;
121	niro	532	rllunpack:
122	niro	1133	push word .pmentry
123			call simple_pm_call
124			ret
125
126			bits 32
127			.pmentry:
128			push edi
129			xor ecx,ecx
130	niro	532	.header:
131	niro	1133	dec esi
132			mov cl,[esi]
133			jcxz .done
134			cmp cl,129
135	niro	532	jae .isrun
136			; Not a run
137	niro	1133	.copy:
138			dec esi
139			mov al,[esi]
140			stosb
141			loop .copy
142	niro	532	jmp .header
143			.isrun:
144	niro	1133	cmp cl,224
145			jae .longrun
146			sub cl,126
147			.dorun:
148			dec esi
149			mov al,[esi]
150	niro	532	rep stosb
151			jmp .header
152	niro	1133	.longrun:
153			sub cl,224
154			mov ch,cl
155			dec esi
156			mov cl,[esi]
157			jmp .dorun
158	niro	532	.done:
159	niro	1133	pop ecx
160			sub ecx,edi
161			neg ecx
162	niro	532	ret
163	niro	1133
164			bits 16