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Merge pull request #214 from greg-king5/cbm-exec

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Make the CBM exec() work in gigantic programs.
This commit is contained in:
Oliver Schmidt 2015-09-30 20:52:31 +02:00
commit 24c2da980b
6 changed files with 63 additions and 27 deletions
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2
asminc/c64.inc
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@ -6,6 +6,8 @@
; ---------------------------------------------------------------------------
; Zero page, Commodore stuff
VARTAB := $2D ; Pointer to start of BASIC variables
MEMSIZE := $37 ; Pointer to highest BASIC RAM location (+1)
TXTPTR := $7A ; Pointer into BASIC source code
TIME := $A0 ; 60 HZ clock
FNAM_LEN := $B7 ; Length of filename

1
asminc/pet.inc
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@ -6,6 +6,7 @@
; ---------------------------------------------------------------------------
; Zero page, Commodore stuff
VARTAB := $2A ; Pointer to start of BASIC variables
MEMSIZE := $34 ; Size of memory installed
TXTPTR := $77 ; Pointer into BASIC source code
TIME := $8D ; 60HZ clock

2
asminc/plus4.inc
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@ -7,6 +7,8 @@
; Zero page, Commodore stuff
TMPPTR := $22 ; Temporary ptr used by BASIC
VARTAB := $2D ; Pointer to start of BASIC variables
MEMSIZE := $37 ; Pointer to highest BASIC RAM location (+1)
TXTPTR := $3B ; Pointer into BASIC source code
TIME := $A3 ; 60HZ clock
FNAM_LEN := $AB ; Length of filename

2
asminc/vic20.inc
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@ -6,6 +6,8 @@
; ---------------------------------------------------------------------------
; Zero page, Commodore stuff
VARTAB := $2D ; Pointer to start of BASIC variables
MEMSIZE := $37 ; Pointer to highest BASIC RAM location (+1)
TXTPTR := $7A ; Pointer into BASIC source code
TIME := $A0 ; 60HZ clock
FNAM_LEN := $B7 ; Length of filename

69
libsrc/cbm/exec.c
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@ -1,7 +1,7 @@
/*
** Program-chaining function for Commodore platforms.
**
** 2013-09-04, Greg King
** 2015-09-27, Greg King
**
** This function exploits the program-chaining feature in CBM BASIC's ROM.
**
@ -32,42 +32,46 @@
/* The struct below is a line of BASIC code. It sits in the LOWCODE segment
** to make sure that it won't be hidden by a ROM when BASIC is re-enabled.
** The line is:
** 0 LOAD""+"" ,01
** 0 CLR:LOAD""+"" ,01
** After this function has written into the line, it might look like this:
** 0 LOAD""+"program name" ,08
** 0 CLR:LOAD""+"program name" ,08
**
** When BASIC's LOAD command asks the Kernal to load a file, it gives the
** Kernal a pointer to a file-name string. CC65's CBM programs use that
** pointer to give a copy of the program's name to main()'s argv[0] parameter.
** But, when BASIC uses a string literal that's in a program, it points
** But, when BASIC uses a string literal that is in a program, it points
** directly to that literal -- in the models that don't use banked RAM
** (Pet/CBM, VIC-20, and 64). The literal is overwritten by the next program
** that's loaded. So, argv[0] would point to machine code. String operations
** that is loaded. So, argv[0] would point to machine code. String operations
** create a new result string -- even when that operation changes nothing. The
** result is put in the string space at the top of BASIC's memory. So, the ""+
** in this BASIC line guarantees that argv[0] will get a name from a safe place.
*/
#pragma data-name(push, "LOWCODE")
static struct line {
const char end_of_line;
const struct line *const next;
const char end_of_line; /* fake previous line */
const struct line* const next;
const unsigned line_num;
const char load_token, quotes[2], add_token, quote;
const char CLR_token, colon, LOAD_token, quotes[2], add_token, quote;
char name[21];
const char comma;
char unit[3];
} basic = {
'\0', &basic + 1, /* high byte of link must be non-zero */
0, 0x93, "\"\"", 0xaa, '\"',
"\" ", /* format: "123:1234567890123456\"" */
'\0', &basic + 1, /* high byte of link must be non-zero */
0, 0x9C, ':', 0x93, "\"\"", 0xAA, '\"',
"\" ", /* format: "123:1234567890123456\"" */
',', "01"
};
#pragma data-name(pop)
/* These values are platform-specific. */
extern const struct line *txtptr;
extern const void* vartab; /* points to BASIC program variables */
#pragma zpsym("vartab")
extern const void* memsize; /* points to top of BASIC RAM */
#pragma zpsym("memsize")
extern const struct line* txtptr; /* points to BASIC code */
#pragma zpsym("txtptr")
extern char basbuf[]; /* BASIC's input buffer */
extern char basbuf[]; /* BASIC's input buffer */
extern void basbuf_len[];
#pragma zpsym("basbuf_len")
@ -75,43 +79,62 @@ extern void basbuf_len[];
int __fastcall__ exec (const char* progname, const char* cmdline)
{
static int fd;
static unsigned char dv, n = 0;
static unsigned char dv, n;
/* Exclude devices that can't load files. */
/* (Use hand optimization, to make smaller code.) */
dv = getcurrentdevice ();
if (dv < 8 && dv != 1 || dv > 30) {
if (dv < 8 && __AX__ != 1 || __AX__ > 30) {
return _mappederrno (9); /* illegal device number */
}
utoa (dv, basic.unit, 10);
/* Don't try to run a program that can't be found. */
fd = open (progname, O_RDONLY);
if (fd < 0) {
return fd;
/* Tape files can be openned only once; skip this test for the Datasette. */
if (dv != 1) {
/* Don't try to run a program that can't be found. */
fd = open (progname, O_RDONLY);
if (fd < 0) {
return -1;
}
close (fd);
}
close (fd);
n = 0;
do {
if ((basic.name[n] = progname[n]) == '\0') {
break;
}
} while (++n < 20); /* truncate long names */
} while (++n < 20); /* truncate long names */
basic.name[n] = '\"';
/* This next part isn't needed by machines that put
** BASIC source and variables in different RAM banks.
*/
#if !defined(__CBM510__) && !defined(__CBM610__) && !defined(__C128__)
/* cc65 program loads might extend beyond the end of the RAM that is allowed
** for BASIC. Then, the LOAD statement would complain that it is "out of
** memory". Some pointers that say where to put BASIC program variables
** must be changed, so that we do not get that error. One pointer is
** changed here; a BASIC CLR statement changes the others.
*/
vartab = (char*)memsize - 256;
#endif
/* Build the next program's argument list. */
basbuf[0] = 0x8f; /* REM token */
basbuf[0] = 0x8F; /* REM token */
basbuf[1] = '\0';
if (cmdline != NULL) {
strncat (basbuf, cmdline, (size_t)basbuf_len - 2);
}
/* Tell the ROM where to find that BASIC program. */
#if defined(__CBM510__) || defined(__CBM610__)
pokewsys ((unsigned)&txtptr, (unsigned)&basic);
#else
txtptr = &basic;
#endif
/* (The return code, in ST, will be destroyed by LOAD.
/* (The return code, in ST [status], will be destroyed by LOAD.
** So, don't bother to set it here.)
*/
exit (__AX__);

14
libsrc/cbm/execvars.s
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@ -20,9 +20,15 @@
.include "vic20.inc"
.endif
.export _txtptr:zp, _basbuf, _basbuf_len:zp
; exec() is written in C.
; Provide the spellings that the C compiler wants to use.
_txtptr := TXTPTR
.ifdef VARTAB
.exportzp _vartab := VARTAB
.exportzp _memsize := MEMSIZE
.endif
_basbuf := BASIC_BUF
_basbuf_len = BASIC_BUF_LEN
.exportzp _txtptr := TXTPTR
.export _basbuf := BASIC_BUF
.exportzp _basbuf_len = BASIC_BUF_LEN