WebSVN – SvarDOS – Diff – /svarcom/trunk/rmodinit.c


 
#include <i86.h>
#include <stdio.h>
#include <string.h>
 
#include "rmod.h"
 
#include "rmodinit.h"
 
 
/* returns segment where rmod is installed */
unsigned short rmod_install(unsigned short envsize) {
  char far *myptr, far *mcb;
  unsigned short far *owner;
  unsigned int rmodseg = 0xffff;
  unsigned int envseg = 0;
 
  /* read my current env segment from PSP */
  _asm {
    push ax
    push bx
    mov bx, 0x2c
    mov ax, [bx]
    mov envseg, ax
    pop bx
    pop ax
  }
 
  printf("original (PSP) env buffer at %04X\r\n", envseg);
  /* if custom envsize requested, convert it to number of paragraphs */
  if (envsize != 0) {
    envsize += 15;
    envsize /= 16;
  }
 
 
  _asm {
    /* link in the UMB memory chain for enabling high-memory allocation (and save initial status on stack) */
    mov ax, 0x5802  /* GET UMB LINK STATE */
    int 0x21
    xor ah, ah
    push ax         /* save link state on stack */
    mov ax, 0x5803  /* SET UMB LINK STATE */
    mov bx, 1
    int 0x21
    /* get current allocation strategy and save it in DX */
    mov ax, 0x5800
    int 0x21
    push ax
    pop dx
    /* set strategy to 'last fit, try high then low memory' */
    mov ax, 0x5801
    mov bx, 0x0082
    int 0x21
    /* ask for a memory block and save the given segment to rmodseg */
    mov ah, 0x48
    mov bx, (rmod_len + 15) / 16
    int 0x21
    jc ALLOC_FAIL
    mov rmodseg, ax
    /* ask for a memory block for the environment and save it to envseg (only if custom size requested) */
    mov bx, envsize
    test bx, bx
    jz ALLOC_FAIL
    mov ah, 0x48
    int 0x21
    jc ALLOC_FAIL
    mov envseg, ax
 
    ALLOC_FAIL:
    /* restore initial allocation strategy */
    mov ax, 0x5801
    mov bx, dx
    int 0x21
    /* restore initial UMB memory link state */
    mov ax, 0x5803
    pop bx       /* pop initial UMB link state from stack */
    int 0x21
  }
 
  if (rmodseg == 0xffff) {
    puts("malloc error");
    return(0xffff);
  }
 
  /* copy rmod to its destination */
  myptr = MK_FP(rmodseg, 0);
  _fmemcpy(myptr, rmod, rmod_len);
 
  /* mark rmod memory as "self owned" */
  mcb = MK_FP(rmodseg - 1, 0);
  owner = (void far *)(mcb + 1);
  *owner = rmodseg;
  _fmemcpy(mcb + 8, "SVARCOM", 8);
 
  /* mark env memory as "self owned" */
 
 
  mcb = MK_FP(envseg - 1, 0);
  owner = (void far *)(mcb + 1);
  *owner = rmodseg;
  _fmemcpy(mcb + 8, "SVARENV", 8);
 
 
  /* write env segment to rmod buffer */
  owner = MK_FP(rmodseg, RMOD_OFFSET_ENVSEG);
  *owner = envseg;
 
  /* set the int22 handler in my PSP to rmod so DOS jumps to rmod after I terminate */
  _asm {
    mov bx, 0x0a                   /* int22 handler is at 0x0A of the PSP */
    mov ax, RMOD_OFFSET_ROUTINE
    mov [bx], ax                   /* int handler offset */
    mov ax, rmodseg
    mov [bx+2], ax                 /* int handler segment */
  }
 
  return(rmodseg);
}
 
 
/* scan memory for rmod, returns its segment if found, 0xffff otherwise */
unsigned short rmod_find(void) {
  unsigned short i;
  unsigned short far *ptrword;
  unsigned char far *ptrbyte;
 
  /* iterate over all paragraphs, looking for my signature */
  for (i = 1; i != 65535; i++) {
    ptrword = MK_FP(i, 0);
    if (ptrword[0] != 0x1983) continue;
    if (ptrword[1] != 0x1985) continue;
    if (ptrword[2] != 0x2017) continue;
    if (ptrword[3] != 0x2019) continue;
    /* extra check: make sure the paragraph before is an MCB block and that it
     * belongs to itself. otherwise I could find the rmod code embedded inside
     * the command.com binary... */
    ptrbyte = MK_FP(i - 1, 0);
    if ((*ptrbyte != 'M') && (*ptrbyte != 'Z')) continue; /* not an MCB */
    ptrword = MK_FP(i - 1, 1);
    if (*ptrword != i) continue; /* not belonging to self */
    return(i);
  }
  return(0xffff);
}
 

Rev 358	Rev 359
1		1
2	`#include <i86.h>`	2	`#include <i86.h>`
3	`#include <stdio.h>`	3	`#include <stdio.h>`
4	`#include <string.h>`	4	`#include <string.h>`
5		5
6	`#include "rmod.h"`	6	`#include "rmod.h"`
7		7
8	`#include "rmodinit.h"`	8	`#include "rmodinit.h"`
9		9
10		10
11	`/* returns segment where rmod is installed */`	11	`/* returns segment where rmod is installed */`
12	`unsigned short rmod_install(unsigned short envsize) {`	12	`unsigned short rmod_install(unsigned short envsize) {`
13	`char far myptr, far mcb;`	13	`char far myptr, far mcb;`
14	`unsigned short far *owner;`	14	`unsigned short far *owner;`
15	`unsigned int rmodseg = 0xffff;`	15	`unsigned int rmodseg = 0xffff;`
16	`unsigned int envseg = 0;`	16	`unsigned int envseg = 0;`
17		17
18	`/* read my current env segment from PSP */`	18	`/* read my current env segment from PSP */`
19	`_asm {`	19	`_asm {`
20	`push ax`	20	`push ax`
21	`push bx`	21	`push bx`
22	`mov bx, 0x2c`	22	`mov bx, 0x2c`
23	`mov ax, [bx]`	23	`mov ax, [bx]`
24	`mov envseg, ax`	24	`mov envseg, ax`
25	`pop bx`	25	`pop bx`
26	`pop ax`	26	`pop ax`
27	`}`	27	`}`
28		28
29	`printf("original (PSP) env buffer at %04X\r\n", envseg);`	29	`printf("original (PSP) env buffer at %04X\r\n", envseg);`
30	`/* if custom envsize requested, convert it to number of paragraphs */`	30	`/* if custom envsize requested, convert it to number of paragraphs */`
31	`if (envsize != 0) {`	31	`if (envsize != 0) {`
32	`envsize += 15;`	32	`envsize += 15;`
33	`envsize /= 16;`	33	`envsize /= 16;`
34	`}`	34	`}`
35		35
36		36
37	`_asm {`	37	`_asm {`
38	`/* link in the UMB memory chain for enabling high-memory allocation (and save initial status on stack) */`	38	`/* link in the UMB memory chain for enabling high-memory allocation (and save initial status on stack) */`
39	`mov ax, 0x5802 /* GET UMB LINK STATE */`	39	`mov ax, 0x5802 /* GET UMB LINK STATE */`
40	`int 0x21`	40	`int 0x21`
41	`xor ah, ah`	41	`xor ah, ah`
42	`push ax /* save link state on stack */`	42	`push ax /* save link state on stack */`
43	`mov ax, 0x5803 /* SET UMB LINK STATE */`	43	`mov ax, 0x5803 /* SET UMB LINK STATE */`
44	`mov bx, 1`	44	`mov bx, 1`
45	`int 0x21`	45	`int 0x21`
46	`/* get current allocation strategy and save it in DX */`	46	`/* get current allocation strategy and save it in DX */`
47	`mov ax, 0x5800`	47	`mov ax, 0x5800`
48	`int 0x21`	48	`int 0x21`
49	`push ax`	49	`push ax`
50	`pop dx`	50	`pop dx`
51	`/* set strategy to 'last fit, try high then low memory' */`	51	`/* set strategy to 'last fit, try high then low memory' */`
52	`mov ax, 0x5801`	52	`mov ax, 0x5801`
53	`mov bx, 0x0082`	53	`mov bx, 0x0082`
54	`int 0x21`	54	`int 0x21`
55	`/* ask for a memory block and save the given segment to rmodseg */`	55	`/* ask for a memory block and save the given segment to rmodseg */`
56	`mov ah, 0x48`	56	`mov ah, 0x48`
57	`mov bx, (rmod_len + 15) / 16`	57	`mov bx, (rmod_len + 15) / 16`
58	`int 0x21`	58	`int 0x21`
59	`jc ALLOC_FAIL`	59	`jc ALLOC_FAIL`
60	`mov rmodseg, ax`	60	`mov rmodseg, ax`
61	`/* ask for a memory block for the environment and save it to envseg (only if custom size requested) */`	61	`/* ask for a memory block for the environment and save it to envseg (only if custom size requested) */`
62	`mov bx, envsize`	62	`mov bx, envsize`
63	`test bx, bx`	63	`test bx, bx`
64	`jz ALLOC_FAIL`	64	`jz ALLOC_FAIL`
65	`mov ah, 0x48`	65	`mov ah, 0x48`
66	`int 0x21`	66	`int 0x21`
67	`jc ALLOC_FAIL`	67	`jc ALLOC_FAIL`
68	`mov envseg, ax`	68	`mov envseg, ax`
69		69
70	`ALLOC_FAIL:`	70	`ALLOC_FAIL:`
71	`/* restore initial allocation strategy */`	71	`/* restore initial allocation strategy */`
72	`mov ax, 0x5801`	72	`mov ax, 0x5801`
73	`mov bx, dx`	73	`mov bx, dx`
74	`int 0x21`	74	`int 0x21`
75	`/* restore initial UMB memory link state */`	75	`/* restore initial UMB memory link state */`
76	`mov ax, 0x5803`	76	`mov ax, 0x5803`
77	`pop bx /* pop initial UMB link state from stack */`	77	`pop bx /* pop initial UMB link state from stack */`
78	`int 0x21`	78	`int 0x21`
79	`}`	79	`}`
80		80
81	`if (rmodseg == 0xffff) {`	81	`if (rmodseg == 0xffff) {`
82	`puts("malloc error");`	82	`puts("malloc error");`
83	`return(0xffff);`	83	`return(0xffff);`
84	`}`	84	`}`
85		85
86	`/* copy rmod to its destination */`	86	`/* copy rmod to its destination */`
87	`myptr = MK_FP(rmodseg, 0);`	87	`myptr = MK_FP(rmodseg, 0);`
88	`_fmemcpy(myptr, rmod, rmod_len);`	88	`_fmemcpy(myptr, rmod, rmod_len);`
89		89
90	`/* mark rmod memory as "self owned" */`	90	`/* mark rmod memory as "self owned" */`
91	`mcb = MK_FP(rmodseg - 1, 0);`	91	`mcb = MK_FP(rmodseg - 1, 0);`
92	`owner = (void far *)(mcb + 1);`	92	`owner = (void far *)(mcb + 1);`
93	`*owner = rmodseg;`	93	`*owner = rmodseg;`
94	`_fmemcpy(mcb + 8, "SVARCOM", 8);`	94	`_fmemcpy(mcb + 8, "SVARCOM", 8);`
95		95
96	`/* mark env memory as "self owned" (only if allocated by me) */`	96	`/* mark env memory as "self owned" */`
97	`if (envsize != 0) {`	-
98	`printf("envseg allocated at %04X:0000 with %u paragraphs\r\n", envseg, envsize);`	-
99	`mcb = MK_FP(envseg - 1, 0);`	97	`mcb = MK_FP(envseg - 1, 0);`
100	`owner = (void far *)(mcb + 1);`	98	`owner = (void far *)(mcb + 1);`
101	`*owner = rmodseg;`	99	`*owner = rmodseg;`
102	`_fmemcpy(mcb + 8, "SVARENV", 8);`	100	`_fmemcpy(mcb + 8, "SVARENV", 8);`
103	`}`	-
104		101
105	`/* write env segment to rmod buffer */`	102	`/* write env segment to rmod buffer */`
106	`owner = MK_FP(rmodseg, RMOD_OFFSET_ENVSEG);`	103	`owner = MK_FP(rmodseg, RMOD_OFFSET_ENVSEG);`
107	`*owner = envseg;`	104	`*owner = envseg;`
108		105
109	`/* set the int22 handler in my PSP to rmod so DOS jumps to rmod after I terminate */`	106	`/* set the int22 handler in my PSP to rmod so DOS jumps to rmod after I terminate */`
110	`_asm {`	107	`_asm {`
111	`mov bx, 0x0a /* int22 handler is at 0x0A of the PSP */`	108	`mov bx, 0x0a /* int22 handler is at 0x0A of the PSP */`
112	`mov ax, RMOD_OFFSET_ROUTINE`	109	`mov ax, RMOD_OFFSET_ROUTINE`
113	`mov [bx], ax /* int handler offset */`	110	`mov [bx], ax /* int handler offset */`
114	`mov ax, rmodseg`	111	`mov ax, rmodseg`
115	`mov [bx+2], ax /* int handler segment */`	112	`mov [bx+2], ax /* int handler segment */`
116	`}`	113	`}`
117		114
118	`return(rmodseg);`	115	`return(rmodseg);`
119	`}`	116	`}`
120		117
121		118
122	`/* scan memory for rmod, returns its segment if found, 0xffff otherwise */`	119	`/* scan memory for rmod, returns its segment if found, 0xffff otherwise */`
123	`unsigned short rmod_find(void) {`	120	`unsigned short rmod_find(void) {`
124	`unsigned short i;`	121	`unsigned short i;`
125	`unsigned short far *ptrword;`	122	`unsigned short far *ptrword;`
126	`unsigned char far *ptrbyte;`	123	`unsigned char far *ptrbyte;`
127		124
128	`/* iterate over all paragraphs, looking for my signature */`	125	`/* iterate over all paragraphs, looking for my signature */`
129	`for (i = 1; i != 65535; i++) {`	126	`for (i = 1; i != 65535; i++) {`
130	`ptrword = MK_FP(i, 0);`	127	`ptrword = MK_FP(i, 0);`
131	`if (ptrword[0] != 0x1983) continue;`	128	`if (ptrword[0] != 0x1983) continue;`
132	`if (ptrword[1] != 0x1985) continue;`	129	`if (ptrword[1] != 0x1985) continue;`
133	`if (ptrword[2] != 0x2017) continue;`	130	`if (ptrword[2] != 0x2017) continue;`
134	`if (ptrword[3] != 0x2019) continue;`	131	`if (ptrword[3] != 0x2019) continue;`
135	`/* extra check: make sure the paragraph before is an MCB block and that it`	132	`/* extra check: make sure the paragraph before is an MCB block and that it`
136	`* belongs to itself. otherwise I could find the rmod code embedded inside`	133	`* belongs to itself. otherwise I could find the rmod code embedded inside`
137	`* the command.com binary... */`	134	`* the command.com binary... */`
138	`ptrbyte = MK_FP(i - 1, 0);`	135	`ptrbyte = MK_FP(i - 1, 0);`
139	`if ((ptrbyte != 'M') && (ptrbyte != 'Z')) continue; /* not an MCB */`	136	`if ((ptrbyte != 'M') && (ptrbyte != 'Z')) continue; /* not an MCB */`
140	`ptrword = MK_FP(i - 1, 1);`	137	`ptrword = MK_FP(i - 1, 1);`
141	`if (ptrword != i) continue; / not belonging to self */`	138	`if (ptrword != i) continue; / not belonging to self */`
142	`return(i);`	139	`return(i);`
143	`}`	140	`}`
144	`return(0xffff);`	141	`return(0xffff);`
145	`}`	142	`}`
146		143

Subversion Repositories SvarDOS

(root)/svarcom/trunk/rmodinit.c @ 896 – Rev 358 → 359