99 lines
2.6 KiB
C
99 lines
2.6 KiB
C
/*
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** Program-chaining function for Commodore platforms.
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**
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** 2013-08-24, Greg King
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**
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** This function exploits the program-chaining feature in CBM BASIC's ROM.
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** It puts the desired program's name and unit number into a LOAD statement.
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** Then, it points BASIC to that statement, so that the ROM will run that
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** statement after this program quits. The ROM will load the next program,
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** and execute it.
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*/
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#include <fcntl.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include <device.h>
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#if defined(__CBM610__)
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# include <cbm610.h>
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#elif defined(__CBM510__)
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# include <cbm510.h>
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#endif
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#pragma data-name(push, "LOWCODE")
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static struct line {
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const char end_of_line;
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const struct line *const next;
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const unsigned line_num;
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const char load_token, quotes[2], add_token, quote;
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char name[21];
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const char comma;
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char unit[3];
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} basic = {
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'\0', &basic + 1, /* high byte must be non-zero */
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0, 0x93,
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/* This string operation copies the name to high BASIC RAM.
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** So, it won't be overwritten when the next program is loaded.
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*/
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"\"\"", 0xaa, '\"',
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"\" ", /* format: "123:1234567890123456\"" */
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',', "01"
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};
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#pragma data-name(pop)
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/* These values are platform-specific. */
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extern const struct line *txtptr;
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#pragma zpsym("txtptr")
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extern char basbuf[]; /* BASIC's input buffer */
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extern void basbuf_len[];
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#pragma zpsym("basbuf_len")
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int __fastcall__ exec (const char* progname, const char* cmdline)
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{
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static int fd;
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static unsigned char dv, n = 0;
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/* Exclude devices that can't load files. */
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dv = getcurrentdevice ();
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if (dv < 8 && dv != 1 || dv > 30) {
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return _mappederrno (9); /* illegal device number */
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}
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utoa (dv, basic.unit, 10);
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/* Don't try to run a program that can't be found. */
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fd = open (progname, O_RDONLY);
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if (fd < 0) {
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return fd;
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}
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close (fd);
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do {
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if ((basic.name[n] = progname[n]) == '\0') {
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break;
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}
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} while (++n < 20); /* truncate long names */
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basic.name[n] = '\"';
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/* Build the next program's argument list. */
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basbuf[0] = 0x8f; /* REM token */
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basbuf[1] = '\0';
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if (cmdline != NULL) {
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strncat (basbuf, cmdline, (size_t)basbuf_len - 2);
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}
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#if defined(__CBM510__) || defined(__CBM610__)
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pokewsys ((unsigned)&txtptr, (unsigned)&basic);
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#else
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txtptr = &basic;
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#endif
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/* (The return code, in ST, will be destroyed by LOAD.
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** So, don't bother to set it here.)
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*/
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exit (__AX__);
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}
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