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


/* This file is part of the SvarCOM project and is published under the terms
 * of the MIT license.
 *
 * Copyright (C) 2021-2022 Mateusz Viste
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */
 
#include <i86.h>
#include <string.h>
 
#include "env.h"
#include "helpers.h"
 
#include "rmodinit.h"
 
 
/* returns far pointer to rmod's settings block on success */
struct rmod_props far *rmod_install(unsigned short envsize, unsigned char *rmodcore, unsigned short rmodcore_len) {
  char far *myptr, far *mcb;
  unsigned short far *owner;
  const unsigned short sizeof_rmodandprops_paras = (0x100 + rmodcore_len + sizeof(struct rmod_props) + 15) / 16;
  unsigned short rmodseg = 0xffff;
  unsigned short envseg, origenvseg;
  struct rmod_props far *res;
 
  /* read my current env segment from PSP and save it */
  envseg = *((unsigned short *)0x2c);
  origenvseg = envseg;
 
  /* printf("original (PSP) env buffer at %04X\r\n", envseg); */
 
  /* if envseg is zero, then enforce our own one (MSDOS 5 does not provide a default env) */
  if ((envseg == 0) && (envsize == 0)) envsize = 256;
 
  /* 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, sizeof_rmodandprops_paras
    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) {
    outputnl("malloc error");
    return(NULL);
  }
 
  /* copy rmod to its destination, prefixed with a copy of my own PSP */
  myptr = MK_FP(rmodseg, 0);
  {
    unsigned short i;
    char *mypsp = (void *)0;
    for (i = 0; i < 0x100; i++) myptr[i] = mypsp[i];
  }
  myptr = MK_FP(rmodseg, 0x100);
  _fmemcpy(myptr, rmodcore, rmodcore_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 "owned by rmod" */
  mcb = MK_FP(envseg - 1, 0);
  owner = (void far *)(mcb + 1);
  *owner = rmodseg;
  _fmemcpy(mcb + 8, "SVARENV", 8);
 
  /* if env block is newly allocated, fill it with a few NULLs */
  if (envsize != 0) {
    owner = MK_FP(envseg, 0);
    owner[0] = 0;
    owner[1] = 0;
  }
 
  /* set CTRL+BREAK handler to rmod */
  _asm {
    push ax
    push dx
    push ds
    mov ax, 0x2523
    mov ds, rmodseg
    mov dx, RMOD_OFFSET_BRKHANDLER
    int 0x21
    pop ds
    pop dx
    pop ax
  }
 
  /* prepare result (rmod props) */
  res = MK_FP(rmodseg, 0x100 + rmodcore_len);
  _fmemset(res, 0, sizeof(*res));  /* zero out */
  res->rmodseg = rmodseg;          /* rmod segment */
  res->inputbuf[0] = 128;          /* input buffer for INT 0x21, AH=0Ah*/
  res->origenvseg = origenvseg;    /* original environment segment */
 
  /* write env segment to rmod's PSP */
  owner = MK_FP(rmodseg, RMOD_OFFSET_ENVSEG);
  *owner = envseg;
 
  /* write boot drive to rmod bootdrive field */
  _asm {
    push ax
    push bx
    push dx
    push ds
    mov ax, 0x3305 /* DOS 4.0+ - GET BOOT DRIVE */
    int 0x21 /* boot drive is in DL now (1=A:, 2=B:, etc) */
    add dl, 'A'-1 /* convert to a proper ASCII letter */
    /* set DS to rmodseg */
    mov ax, rmodseg
    mov ds, ax
    /* write boot drive to rmod bootdrive field */
    mov bx, RMOD_OFFSET_BOOTDRIVE
    mov [bx], dl
    pop ds
    pop dx
    pop bx
    pop ax
  }
 
  /* save my original parent in rmod's memory */
  res->origparent = *((unsigned long *)0x0a); /* original parent seg:off is at 0x0a of my PSP */
 
  /* set the int22 handler in my PSP to rmod so DOS jumps to rmod after I
   * terminate and save the original handler in rmod's memory */
  {
    unsigned short *ptr = (void *)0x0a; /* int22 handler is at 0x0A of the PSP */
    ptr[0] = RMOD_OFFSET_ROUTINE;
    ptr[1] = rmodseg;
  }
 
  return(res);
}
 
 
/* look up my parent: if it's rmod then return a ptr to its props struct,
 * otherwise return NULL */
struct rmod_props far *rmod_find(unsigned short rmodcore_len) {
  unsigned short *parent = (void *)0x0C; /* parent's seg in PSP[Ch] ("prev. int22 handler") */
  unsigned short far *ptr;
  const unsigned short sig[] = {0x1983, 0x1985, 0x2017, 0x2019};
  unsigned char *cmdtail = (void *)0x80;
  unsigned char i;
  /* is it rmod? */
  ptr = MK_FP(*parent, 0x100);
  for (i = 0; i < 4; i++) if (ptr[i] != sig[i]) return(NULL);
  /* match successfull (rmod is my parent) - but is it really a respawn?
   * command-line tail should contain a single character '\r' */
  if ((cmdtail[0] != 1) || (cmdtail[1] != '\n')) return(NULL);
  cmdtail[0] = 0;
  cmdtail[1] = '\r';
  /* */
  return(MK_FP(*parent, 0x100 + rmodcore_len));
}
 
 
/* update rmod's pointer to comspec */
void rmod_updatecomspecptr(unsigned short rmod_seg, unsigned short env_seg) {
  unsigned short far *comspecptr = MK_FP(rmod_seg, RMOD_OFFSET_COMSPECPTR);
  char far *comspecfp = env_lookup_val(env_seg, "COMSPEC");
  if (comspecfp != NULL) {
    *comspecptr = FP_OFF(comspecfp);
  } else {
    *comspecptr = 0;
  }
}
 
 
/* allocates bytes of far memory, flags it as belonging to rmod
 * the new block can be optionally flagged as 'ident' (if not null) and zero
 * out the newly allocated memory.
 * returns a far ptr to the allocated block, or NULL on error */
void far *rmod_fcalloc(unsigned short bytes, unsigned short rmod_seg, char *ident) {
  unsigned short far *owner;
  unsigned short newseg = 0;
 
  /* ask DOS for a memory block (as high as possible) */
  _asm {
    push bx /* save initial value in BX so I can restore it later */
 
    /* get current allocation strategy and save it on stack */
    mov ax, 0x5800
    int 0x21
    push ax
 
    /* 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  /* Allocate Memory */
    mov bx, bytes
    add bx, 15    /* convert bytes to paragraphs */
    shr bx, 1     /* bx /= 16 */
    shr bx, 1
    shr bx, 1
    shr bx, 1
    int 0x21
 
    /* error handling */
    jc FAIL
 
    /* save newly allocated segment to newseg */
    mov newseg, ax
 
    FAIL:
    /* restore initial allocation strategy */
    mov ax, 0x5801
    pop bx
    int 0x21
 
    pop bx /* restore BX to its initial value */
  }
 
  if (newseg == 0) return(NULL);
 
  /* mark memory as "owned by rmod" */
  owner = (void far *)(MK_FP(newseg - 1, 1));
  *owner = rmod_seg;
 
  /* set the MCB description to ident, if provided */
  if (ident) {
    char far *mcbdesc = MK_FP(newseg - 1, 8);
    int i;
    _fmemset(mcbdesc, 0, 8);
    for (i = 0; (i < 8) && (ident[i] != 0); i++) { /* field's length is limited to 8 bytes max */
      mcbdesc[i] = ident[i];
    }
  }
 
  /* zero out the memory before handing it out */
  _fmemset(MK_FP(newseg, 0), 0, bytes);
 
  return(MK_FP(newseg, 0));
}
 
 
/* free memory previously allocated by rmod_fcalloc() */
void rmod_ffree(void far *ptr) {
  unsigned short ptrseg;
  unsigned short myseg = 0;
  unsigned short far *owner;
  if (ptr == NULL) return;
  ptrseg = FP_SEG(ptr);
 
  /* get my own segment */
  _asm {
    mov myseg, cs
  }
 
  /* mark memory in MCB as my own, otherwise DOS might refuse to free it */
  owner = MK_FP(ptrseg - 1, 1);
  *owner = myseg;
 
  /* free the memory block */
  _asm {
    push es
    mov ah, 0x49  /* Free Memory Block */
    mov es, ptrseg
    int 0x21
    pop es
  }
}
 

Rev 949	Rev 957
1	`/* This file is part of the SvarCOM project and is published under the terms`	1	`/* This file is part of the SvarCOM project and is published under the terms`
2	`* of the MIT license.`	2	`* of the MIT license.`
3	`*`	3	`*`
4	`* Copyright (C) 2021-2022 Mateusz Viste`	4	`* Copyright (C) 2021-2022 Mateusz Viste`
5	`*`	5	`*`
6	`* Permission is hereby granted, free of charge, to any person obtaining a`	6	`* Permission is hereby granted, free of charge, to any person obtaining a`
7	`* copy of this software and associated documentation files (the "Software"),`	7	`* copy of this software and associated documentation files (the "Software"),`
8	`* to deal in the Software without restriction, including without limitation`	8	`* to deal in the Software without restriction, including without limitation`
9	`* the rights to use, copy, modify, merge, publish, distribute, sublicense,`	9	`* the rights to use, copy, modify, merge, publish, distribute, sublicense,`
10	`* and/or sell copies of the Software, and to permit persons to whom the`	10	`* and/or sell copies of the Software, and to permit persons to whom the`
11	`* Software is furnished to do so, subject to the following conditions:`	11	`* Software is furnished to do so, subject to the following conditions:`
12	`*`	12	`*`
13	`* The above copyright notice and this permission notice shall be included in`	13	`* The above copyright notice and this permission notice shall be included in`
14	`* all copies or substantial portions of the Software.`	14	`* all copies or substantial portions of the Software.`
15	`*`	15	`*`
16	`* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR`	16	`* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR`
17	`* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,`	17	`* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,`
18	`* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE`	18	`* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE`
19	`* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER`	19	`* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER`
20	`* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING`	20	`* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING`
21	`* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER`	21	`* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER`
22	`* DEALINGS IN THE SOFTWARE.`	22	`* DEALINGS IN THE SOFTWARE.`
23	`*/`	23	`*/`
24		24
25	`#include <i86.h>`	25	`#include <i86.h>`
26	`#include <string.h>`	26	`#include <string.h>`
27		27
28	`#include "env.h"`	28	`#include "env.h"`
29	`#include "helpers.h"`	29	`#include "helpers.h"`
30		30
31	`#include "rmodinit.h"`	31	`#include "rmodinit.h"`
32		32
33		33
34	`/* returns far pointer to rmod's settings block on success */`	34	`/* returns far pointer to rmod's settings block on success */`
35	`struct rmod_props far rmod_install(unsigned short envsize, unsigned char rmodcore, unsigned short rmodcore_len) {`	35	`struct rmod_props far rmod_install(unsigned short envsize, unsigned char rmodcore, unsigned short rmodcore_len) {`
36	`char far myptr, far mcb;`	36	`char far myptr, far mcb;`
37	`unsigned short far *owner;`	37	`unsigned short far *owner;`
38	`const unsigned short sizeof_rmodandprops_paras = (0x100 + rmodcore_len + sizeof(struct rmod_props) + 15) / 16;`	38	`const unsigned short sizeof_rmodandprops_paras = (0x100 + rmodcore_len + sizeof(struct rmod_props) + 15) / 16;`
39	`unsigned short rmodseg = 0xffff;`	39	`unsigned short rmodseg = 0xffff;`
40	`unsigned short envseg, origenvseg;`	40	`unsigned short envseg, origenvseg;`
41	`struct rmod_props far *res;`	41	`struct rmod_props far *res;`
42		42
43	`/* read my current env segment from PSP and save it */`	43	`/* read my current env segment from PSP and save it */`
44	`envseg = ((unsigned short )0x2c);`	44	`envseg = ((unsigned short )0x2c);`
45	`origenvseg = envseg;`	45	`origenvseg = envseg;`
46		46
47	`/* printf("original (PSP) env buffer at %04X\r\n", envseg); */`	47	`/* printf("original (PSP) env buffer at %04X\r\n", envseg); */`
48		48
49	`/* if envseg is zero, then enforce our own one (MSDOS 5 does not provide a default env) */`	49	`/* if envseg is zero, then enforce our own one (MSDOS 5 does not provide a default env) */`
50	`if ((envseg == 0) && (envsize == 0)) envsize = 256;`	50	`if ((envseg == 0) && (envsize == 0)) envsize = 256;`
51		51
52	`/* if custom envsize requested, convert it to number of paragraphs */`	52	`/* if custom envsize requested, convert it to number of paragraphs */`
53	`if (envsize != 0) {`	53	`if (envsize != 0) {`
54	`envsize += 15;`	54	`envsize += 15;`
55	`envsize /= 16;`	55	`envsize /= 16;`
56	`}`	56	`}`
57		57
58	`_asm {`	58	`_asm {`
59	`/* link in the UMB memory chain for enabling high-memory allocation (and save initial status on stack) */`	59	`/* link in the UMB memory chain for enabling high-memory allocation (and save initial status on stack) */`
60	`mov ax, 0x5802 /* GET UMB LINK STATE */`	60	`mov ax, 0x5802 /* GET UMB LINK STATE */`
61	`int 0x21`	61	`int 0x21`
62	`xor ah, ah`	62	`xor ah, ah`
63	`push ax /* save link state on stack */`	63	`push ax /* save link state on stack */`
64	`mov ax, 0x5803 /* SET UMB LINK STATE */`	64	`mov ax, 0x5803 /* SET UMB LINK STATE */`
65	`mov bx, 1`	65	`mov bx, 1`
66	`int 0x21`	66	`int 0x21`
67	`/* get current allocation strategy and save it in DX */`	67	`/* get current allocation strategy and save it in DX */`
68	`mov ax, 0x5800`	68	`mov ax, 0x5800`
69	`int 0x21`	69	`int 0x21`
70	`push ax`	70	`push ax`
71	`pop dx`	71	`pop dx`
72	`/* set strategy to 'last fit, try high then low memory' */`	72	`/* set strategy to 'last fit, try high then low memory' */`
73	`mov ax, 0x5801`	73	`mov ax, 0x5801`
74	`mov bx, 0x0082`	74	`mov bx, 0x0082`
75	`int 0x21`	75	`int 0x21`
76	`/* ask for a memory block and save the given segment to rmodseg */`	76	`/* ask for a memory block and save the given segment to rmodseg */`
77	`mov ah, 0x48`	77	`mov ah, 0x48`
78	`mov bx, sizeof_rmodandprops_paras`	78	`mov bx, sizeof_rmodandprops_paras`
79	`int 0x21`	79	`int 0x21`
80	`jc ALLOC_FAIL`	80	`jc ALLOC_FAIL`
81	`mov rmodseg, ax`	81	`mov rmodseg, ax`
82	`/* ask for a memory block for the environment and save it to envseg (only if custom size requested) */`	82	`/* ask for a memory block for the environment and save it to envseg (only if custom size requested) */`
83	`mov bx, envsize`	83	`mov bx, envsize`
84	`test bx, bx`	84	`test bx, bx`
85	`jz ALLOC_FAIL`	85	`jz ALLOC_FAIL`
86	`mov ah, 0x48`	86	`mov ah, 0x48`
87	`int 0x21`	87	`int 0x21`
88	`jc ALLOC_FAIL`	88	`jc ALLOC_FAIL`
89	`mov envseg, ax`	89	`mov envseg, ax`
90		90
91	`ALLOC_FAIL:`	91	`ALLOC_FAIL:`
92	`/* restore initial allocation strategy */`	92	`/* restore initial allocation strategy */`
93	`mov ax, 0x5801`	93	`mov ax, 0x5801`
94	`mov bx, dx`	94	`mov bx, dx`
95	`int 0x21`	95	`int 0x21`
96	`/* restore initial UMB memory link state */`	96	`/* restore initial UMB memory link state */`
97	`mov ax, 0x5803`	97	`mov ax, 0x5803`
98	`pop bx /* pop initial UMB link state from stack */`	98	`pop bx /* pop initial UMB link state from stack */`
99	`int 0x21`	99	`int 0x21`
100	`}`	100	`}`
101		101
102	`if (rmodseg == 0xffff) {`	102	`if (rmodseg == 0xffff) {`
103	`outputnl("malloc error");`	103	`outputnl("malloc error");`
104	`return(NULL);`	104	`return(NULL);`
105	`}`	105	`}`
106		106
107	`/* copy rmod to its destination, prefixed with a copy of my own PSP */`	107	`/* copy rmod to its destination, prefixed with a copy of my own PSP */`
108	`myptr = MK_FP(rmodseg, 0);`	108	`myptr = MK_FP(rmodseg, 0);`
109	`{`	109	`{`
110	`unsigned short i;`	110	`unsigned short i;`
111	`char mypsp = (void )0;`	111	`char mypsp = (void )0;`
112	`for (i = 0; i < 0x100; i++) myptr[i] = mypsp[i];`	112	`for (i = 0; i < 0x100; i++) myptr[i] = mypsp[i];`
113	`}`	113	`}`
114	`myptr = MK_FP(rmodseg, 0x100);`	114	`myptr = MK_FP(rmodseg, 0x100);`
115	`_fmemcpy(myptr, rmodcore, rmodcore_len);`	115	`_fmemcpy(myptr, rmodcore, rmodcore_len);`
116		116
117	`/* mark rmod memory as "self owned" */`	117	`/* mark rmod memory as "self owned" */`
118	`mcb = MK_FP(rmodseg - 1, 0);`	118	`mcb = MK_FP(rmodseg - 1, 0);`
119	`owner = (void far *)(mcb + 1);`	119	`owner = (void far *)(mcb + 1);`
120	`*owner = rmodseg;`	120	`*owner = rmodseg;`
121	`_fmemcpy(mcb + 8, "SVARCOM", 8);`	121	`_fmemcpy(mcb + 8, "SVARCOM", 8);`
122		122
123	`/* mark env memory as "owned by rmod" */`	123	`/* mark env memory as "owned by rmod" */`
124	`mcb = MK_FP(envseg - 1, 0);`	124	`mcb = MK_FP(envseg - 1, 0);`
125	`owner = (void far *)(mcb + 1);`	125	`owner = (void far *)(mcb + 1);`
126	`*owner = rmodseg;`	126	`*owner = rmodseg;`
127	`_fmemcpy(mcb + 8, "SVARENV", 8);`	127	`_fmemcpy(mcb + 8, "SVARENV", 8);`
128		128
129	`/* if env block is newly allocated, fill it with a few NULLs */`	129	`/* if env block is newly allocated, fill it with a few NULLs */`
130	`if (envsize != 0) {`	130	`if (envsize != 0) {`
131	`owner = MK_FP(envseg, 0);`	131	`owner = MK_FP(envseg, 0);`
132	`owner[0] = 0;`	132	`owner[0] = 0;`
133	`owner[1] = 0;`	133	`owner[1] = 0;`
134	`}`	134	`}`
135		135
136	`/* set CTRL+BREAK handler to rmod */`	136	`/* set CTRL+BREAK handler to rmod */`
137	`_asm {`	137	`_asm {`
138	`push ax`	138	`push ax`
139	`push dx`	139	`push dx`
140	`push ds`	140	`push ds`
141	`mov ax, 0x2523`	141	`mov ax, 0x2523`
142	`mov ds, rmodseg`	142	`mov ds, rmodseg`
143	`mov dx, RMOD_OFFSET_BRKHANDLER`	143	`mov dx, RMOD_OFFSET_BRKHANDLER`
144	`int 0x21`	144	`int 0x21`
145	`pop ds`	145	`pop ds`
146	`pop dx`	146	`pop dx`
147	`pop ax`	147	`pop ax`
148	`}`	148	`}`
149		149
150	`/* prepare result (rmod props) */`	150	`/* prepare result (rmod props) */`
151	`res = MK_FP(rmodseg, 0x100 + rmodcore_len);`	151	`res = MK_FP(rmodseg, 0x100 + rmodcore_len);`
152	`_fmemset(res, 0, sizeof(res)); / zero out */`	152	`_fmemset(res, 0, sizeof(res)); / zero out */`
153	`res->rmodseg = rmodseg; /* rmod segment */`	153	`res->rmodseg = rmodseg; /* rmod segment */`
154	`res->inputbuf[0] = 128; /* input buffer for INT 0x21, AH=0Ah*/`	154	`res->inputbuf[0] = 128; /* input buffer for INT 0x21, AH=0Ah*/`
155	`res->origenvseg = origenvseg; /* original environment segment */`	155	`res->origenvseg = origenvseg; /* original environment segment */`
156		156
157	`/* write env segment to rmod's PSP */`	157	`/* write env segment to rmod's PSP */`
158	`owner = MK_FP(rmodseg, RMOD_OFFSET_ENVSEG);`	158	`owner = MK_FP(rmodseg, RMOD_OFFSET_ENVSEG);`
159	`*owner = envseg;`	159	`*owner = envseg;`
160		160
161	`/* write boot drive to rmod bootdrive field */`	161	`/* write boot drive to rmod bootdrive field */`
162	`_asm {`	162	`_asm {`
163	`push ax`	163	`push ax`
164	`push bx`	164	`push bx`
165	`push dx`	165	`push dx`
166	`push ds`	166	`push ds`
167	`mov ax, 0x3305 /* DOS 4.0+ - GET BOOT DRIVE */`	167	`mov ax, 0x3305 /* DOS 4.0+ - GET BOOT DRIVE */`
168	`int 0x21 /* boot drive is in DL now (1=A:, 2=B:, etc) */`	168	`int 0x21 /* boot drive is in DL now (1=A:, 2=B:, etc) */`
169	`add dl, 'A'-1 /* convert to a proper ASCII letter */`	169	`add dl, 'A'-1 /* convert to a proper ASCII letter */`
170	`/* set DS to rmodseg */`	170	`/* set DS to rmodseg */`
171	`mov ax, rmodseg`	171	`mov ax, rmodseg`
172	`mov ds, ax`	172	`mov ds, ax`
173	`/* write boot drive to rmod bootdrive field */`	173	`/* write boot drive to rmod bootdrive field */`
174	`mov bx, RMOD_OFFSET_BOOTDRIVE`	174	`mov bx, RMOD_OFFSET_BOOTDRIVE`
175	`mov [bx], dl`	175	`mov [bx], dl`
176	`pop ds`	176	`pop ds`
177	`pop dx`	177	`pop dx`
178	`pop bx`	178	`pop bx`
179	`pop ax`	179	`pop ax`
180	`}`	180	`}`
181		181
182	`/* save my original parent in rmod's memory */`	182	`/* save my original parent in rmod's memory */`
183	`res->origparent = ((unsigned long )0x0a); /* original parent seg:off is at 0x0a of my PSP */`	183	`res->origparent = ((unsigned long )0x0a); /* original parent seg:off is at 0x0a of my PSP */`
184		184
185	`/* set the int22 handler in my PSP to rmod so DOS jumps to rmod after I`	185	`/* set the int22 handler in my PSP to rmod so DOS jumps to rmod after I`
186	`* terminate and save the original handler in rmod's memory */`	186	`* terminate and save the original handler in rmod's memory */`
187	`{`	187	`{`
188	`unsigned short ptr = (void )0x0a; /* int22 handler is at 0x0A of the PSP */`	188	`unsigned short ptr = (void )0x0a; /* int22 handler is at 0x0A of the PSP */`
189	`ptr[0] = RMOD_OFFSET_ROUTINE;`	189	`ptr[0] = RMOD_OFFSET_ROUTINE;`
190	`ptr[1] = rmodseg;`	190	`ptr[1] = rmodseg;`
191	`}`	191	`}`
192		192
193	`return(res);`	193	`return(res);`
194	`}`	194	`}`
195		195
196		196
197	`/* look up my parent: if it's rmod then return a ptr to its props struct,`	197	`/* look up my parent: if it's rmod then return a ptr to its props struct,`
198	`* otherwise return NULL */`	198	`* otherwise return NULL */`
199	`struct rmod_props far *rmod_find(unsigned short rmodcore_len) {`	199	`struct rmod_props far *rmod_find(unsigned short rmodcore_len) {`
200	`unsigned short parent = (void )0x0C; /* parent's seg in PSP[Ch] ("prev. int22 handler") */`	200	`unsigned short parent = (void )0x0C; /* parent's seg in PSP[Ch] ("prev. int22 handler") */`
201	`unsigned short far *ptr;`	201	`unsigned short far *ptr;`
202	`const unsigned short sig[] = {0x1983, 0x1985, 0x2017, 0x2019};`	202	`const unsigned short sig[] = {0x1983, 0x1985, 0x2017, 0x2019};`
203	`unsigned char cmdtail = (void )0x80;`	203	`unsigned char cmdtail = (void )0x80;`
204	`unsigned char i;`	204	`unsigned char i;`
205	`/* is it rmod? */`	205	`/* is it rmod? */`
206	`ptr = MK_FP(*parent, 0x100);`	206	`ptr = MK_FP(*parent, 0x100);`
207	`for (i = 0; i < 4; i++) if (ptr[i] != sig[i]) return(NULL);`	207	`for (i = 0; i < 4; i++) if (ptr[i] != sig[i]) return(NULL);`
208	`/* match successfull (rmod is my parent) - but is it really a respawn?`	208	`/* match successfull (rmod is my parent) - but is it really a respawn?`
209	`* command-line tail should contain a single character '\r' */`	209	`* command-line tail should contain a single character '\r' */`
210	`if ((cmdtail[0] != 1) \|\| (cmdtail[1] != '\n')) return(NULL);`	210	`if ((cmdtail[0] != 1) \|\| (cmdtail[1] != '\n')) return(NULL);`
211	`cmdtail[0] = 0;`	211	`cmdtail[0] = 0;`
212	`cmdtail[1] = '\r';`	212	`cmdtail[1] = '\r';`
213	`/* */`	213	`/* */`
214	`return(MK_FP(*parent, 0x100 + rmodcore_len));`	214	`return(MK_FP(*parent, 0x100 + rmodcore_len));`
215	`}`	215	`}`
216		216
217		217
218	`/* update rmod's pointer to comspec */`	218	`/* update rmod's pointer to comspec */`
219	`void rmod_updatecomspecptr(unsigned short rmod_seg, unsigned short env_seg) {`	219	`void rmod_updatecomspecptr(unsigned short rmod_seg, unsigned short env_seg) {`
220	`unsigned short far *comspecptr = MK_FP(rmod_seg, RMOD_OFFSET_COMSPECPTR);`	220	`unsigned short far *comspecptr = MK_FP(rmod_seg, RMOD_OFFSET_COMSPECPTR);`
221	`char far *comspecfp = env_lookup_val(env_seg, "COMSPEC");`	221	`char far *comspecfp = env_lookup_val(env_seg, "COMSPEC");`
222	`if (comspecfp != NULL) {`	222	`if (comspecfp != NULL) {`
223	`*comspecptr = FP_OFF(comspecfp);`	223	`*comspecptr = FP_OFF(comspecfp);`
224	`} else {`	224	`} else {`
225	`*comspecptr = 0;`	225	`*comspecptr = 0;`
226	`}`	226	`}`
227	`}`	227	`}`
228		228
229		229
230	`/* allocates bytes of far memory, flags it as belonging to rmod`	230	`/* allocates bytes of far memory, flags it as belonging to rmod`
231	`* the new block can be optionally flagged as 'ident' (if not null)`	231	`* the new block can be optionally flagged as 'ident' (if not null) and zero`
-		232	`* out the newly allocated memory.`
232	`* returns a far ptr to the allocated block, or NULL on error */`	233	`* returns a far ptr to the allocated block, or NULL on error */`
233	`void far rmod_fmalloc(unsigned short bytes, unsigned short rmod_seg, char ident) {`	234	`void far rmod_fcalloc(unsigned short bytes, unsigned short rmod_seg, char ident) {`
234	`unsigned short far *owner;`	235	`unsigned short far *owner;`
235	`unsigned short newseg = 0;`	236	`unsigned short newseg = 0;`
236		237
237	`/* ask DOS for a memory block (as high as possible) */`	238	`/* ask DOS for a memory block (as high as possible) */`
238	`_asm {`	239	`_asm {`
239	`push bx /* save initial value in BX so I can restore it later */`	240	`push bx /* save initial value in BX so I can restore it later */`
240		241
241	`/* get current allocation strategy and save it on stack */`	242	`/* get current allocation strategy and save it on stack */`
242	`mov ax, 0x5800`	243	`mov ax, 0x5800`
243	`int 0x21`	244	`int 0x21`
244	`push ax`	245	`push ax`
245		246
246	`/* set strategy to 'last fit, try high then low memory' */`	247	`/* set strategy to 'last fit, try high then low memory' */`
247	`mov ax, 0x5801`	248	`mov ax, 0x5801`
248	`mov bx, 0x0082`	249	`mov bx, 0x0082`
249	`int 0x21`	250	`int 0x21`
250		251
251	`/* ask for a memory block and save the given segment to rmodseg */`	252	`/* ask for a memory block and save the given segment to rmodseg */`
252	`mov ah, 0x48 /* Allocate Memory */`	253	`mov ah, 0x48 /* Allocate Memory */`
253	`mov bx, bytes`	254	`mov bx, bytes`
254	`add bx, 15 /* convert bytes to paragraphs */`	255	`add bx, 15 /* convert bytes to paragraphs */`
255	`shr bx, 1 /* bx /= 16 */`	256	`shr bx, 1 /* bx /= 16 */`
256	`shr bx, 1`	257	`shr bx, 1`
257	`shr bx, 1`	258	`shr bx, 1`
258	`shr bx, 1`	259	`shr bx, 1`
259	`int 0x21`	260	`int 0x21`
260		261
261	`/* error handling */`	262	`/* error handling */`
262	`jc FAIL`	263	`jc FAIL`
263		264
264	`/* save newly allocated segment to newseg */`	265	`/* save newly allocated segment to newseg */`
265	`mov newseg, ax`	266	`mov newseg, ax`
266		267
267	`FAIL:`	268	`FAIL:`
268	`/* restore initial allocation strategy */`	269	`/* restore initial allocation strategy */`
269	`mov ax, 0x5801`	270	`mov ax, 0x5801`
270	`pop bx`	271	`pop bx`
271	`int 0x21`	272	`int 0x21`
272		273
273	`pop bx /* restore BX to its initial value */`	274	`pop bx /* restore BX to its initial value */`
274	`}`	275	`}`
275		276
276	`if (newseg == 0) return(NULL);`	277	`if (newseg == 0) return(NULL);`
277		278
278	`/* mark memory as "owned by rmod" */`	279	`/* mark memory as "owned by rmod" */`
279	`owner = (void far *)(MK_FP(newseg - 1, 1));`	280	`owner = (void far *)(MK_FP(newseg - 1, 1));`
280	`*owner = rmod_seg;`	281	`*owner = rmod_seg;`
281		282
282	`/* set the MCB description to ident, if provided */`	283	`/* set the MCB description to ident, if provided */`
283	`if (ident) {`	284	`if (ident) {`
284	`char far *mcbdesc = MK_FP(newseg - 1, 8);`	285	`char far *mcbdesc = MK_FP(newseg - 1, 8);`
285	`int i;`	286	`int i;`
286	`_fmemset(mcbdesc, 0, 8);`	287	`_fmemset(mcbdesc, 0, 8);`
287	`for (i = 0; (i < 8) && (ident[i] != 0); i++) { /* field's length is limited to 8 bytes max */`	288	`for (i = 0; (i < 8) && (ident[i] != 0); i++) { /* field's length is limited to 8 bytes max */`
288	`mcbdesc[i] = ident[i];`	289	`mcbdesc[i] = ident[i];`
289	`}`	290	`}`
290	`}`	291	`}`
291		292
-		293	`/* zero out the memory before handing it out */`
-		294	`_fmemset(MK_FP(newseg, 0), 0, bytes);`
-		295
292	`return(MK_FP(newseg, 0));`	296	`return(MK_FP(newseg, 0));`
293	`}`	297	`}`
294		298
295		299
296	`/* free memory previously allocated by rmod_ffmalloc() */`	300	`/* free memory previously allocated by rmod_fcalloc() */`
297	`void rmod_ffree(void far *ptr) {`	301	`void rmod_ffree(void far *ptr) {`
298	`unsigned short ptrseg;`	302	`unsigned short ptrseg;`
299	`unsigned short myseg = 0;`	303	`unsigned short myseg = 0;`
300	`unsigned short far *owner;`	304	`unsigned short far *owner;`
301	`if (ptr == NULL) return;`	305	`if (ptr == NULL) return;`
302	`ptrseg = FP_SEG(ptr);`	306	`ptrseg = FP_SEG(ptr);`
303		307
304	`/* get my own segment */`	308	`/* get my own segment */`
305	`_asm {`	309	`_asm {`
306	`mov myseg, cs`	310	`mov myseg, cs`
307	`}`	311	`}`
308		312
309	`/* mark memory in MCB as my own, otherwise DOS might refuse to free it */`	313	`/* mark memory in MCB as my own, otherwise DOS might refuse to free it */`
310	`owner = MK_FP(ptrseg - 1, 1);`	314	`owner = MK_FP(ptrseg - 1, 1);`
311	`*owner = myseg;`	315	`*owner = myseg;`
312		316
313	`/* free the memory block */`	317	`/* free the memory block */`
314	`_asm {`	318	`_asm {`
315	`push es`	319	`push es`
316	`mov ah, 0x49 /* Free Memory Block */`	320	`mov ah, 0x49 /* Free Memory Block */`
317	`mov es, ptrseg`	321	`mov es, ptrseg`
318	`int 0x21`	322	`int 0x21`
319	`pop es`	323	`pop es`
320	`}`	324	`}`
321	`}`	325	`}`
322		326

Subversion Repositories SvarDOS

(root)/svarcom/trunk/rmodinit.c – Rev 949 → 957