This time, the BDS C Compiler.
Go to Leo Zolman's BDS C web page and download the release file bdsc-all.zip.
BDS C comes with extensive documentation in the file bdsc-guide.pdf, but for the purposes of a simple demo, you can do the following. Unzip the file and copy these files to an SD card, and then transfer them to a CP/M drive:
BDSCIO.H C.CCC CC.COM CC2.COM
CLINK.COM DEFF.CRL DEFF2.CRL STDIO.H
The example program TAIL.C used in the demonstration was found here.
Here is an even shorter example C program that I wrote. I entered it as the filename EX1.C:
/* BDS C example 1 */
#include
main(argc,argv)
char **argv;
{
int i;
printf("Example Program 1\n");
for (i=1; i <=10; i++) {
printf("%d\n", i);
}
return 0;
}
Here is a sample session showing EX1.C and TAIL.C being compiled, linked, and run (commands typed by the user are in bold).
B>dir
B: EX1 C : NQUEENS C : BDSCIO H : C CCC
B: CC COM : CC2 COM : CLINK COM : DEFF CRL
B: DEFF2 CRL : STDIO H : TAIL C
B>cc ex1
BD Software C Compiler v1.60 (part I)
37K elbowroom
BD Software C Compiler v1.60 (part II)
34K to spare
B>clink ex1
BD Software C Linker v1.60
Last code address: 0E8D
Externals start at 0E8E, occupy 0006 bytes, last byte at 0E93
Top of memory: E805
Stack space: D972
Writing output...
46K link space remaining
B>ex1
Example Program 1
1
2
3
4
5
6
7
8
9
10
B>cc tail
BD Software C Compiler v1.60 (part I)
36K elbowroom
BD Software C Compiler v1.60 (part II)
33K to spare
B>clink tail
BD Software C Linker v1.60
Last code address: 1402
Externals start at 1403, occupy 0006 bytes, last byte at 1408
Top of memory: E805
Stack space: D3FD
Writing output...
44K link space remaining
B>tail -10 tail.c
}
int lastchar(c)
char c;
{
return (!c) || (c == CPMEOF);
}
B>tail
Usage: tail [-#]
B>dir
B: TAIL CRL : TAIL COM : NQUEENS CRL : NQUEENS COM
B: EX1 C : NQUEENS C : BDSCIO H : C CCC
B: CC COM : CC2 COM : CLINK COM : DEFF CRL
B: DEFF2 CRL : STDIO H : TAIL C : EX1 CRL
B: EX1 COM
Finally, here is the N Queens example program shown in the YouTube video. It will take a while to run to completion. First the source code, followed by example output.
/* Solve the n queens problem */
#include
#define MAX_N 8
int board[MAX_N*MAX_N];
int tries;
int solutions;
int n;
int nsq;
int cache[MAX_N+1]; /* get some savings by caching last position */
/* display the board */
void print_board()
{
int i;
printf("+");
for (i = 0; i < n ; i++)
printf("---");
printf("+\n");
for (i = 0; i < nsq ; i++) {
if ((i % n) == 0)
printf("|");
if (board[i])
printf(" Q ");
else
printf(" . ");
if (((i+1) % n) == 0)
printf("|\n");
}
printf("+");
for (i = 0; i < n ; i++)
printf("---");
printf("+\n");
}
/* find position of a piece */
int piece(n)
{
int i;
/* first try the cache */
if (board[cache[n]] == n)
return cache[n];
for (i = 0 ; i < nsq ; i++)
if (board[i] == n) {
cache[n] = i; /* cache it for next time */
return i;
}
return -1;
}
/* see if board is a solution */
void check_board()
{
int i, p, r, c, j;
/* loop over all pieces */
for (i = 1 ; i <= n ; i++) {
p = piece(i);
/* not a solution if piece in same row */
r = p / n;
for (c = 0 ; c < n ; c++) {
if (board[r*n+c] != 0 && board[r*n+c] != i)
return;
}
/* not a solution if piece in same column */
c = p % n;
for (r = 0 ; r < n ; r++) {
if (board[r*n+c] != 0 && board[r*n+c] != i)
return;
}
/* not a solution if piece in same \ diagonal */
for (j = -n ; j < n ; j++) {
r = p / n + j;
c = p % n + j;
if ((r >= 0) && (r < n) && (c >= 0) && (c < n) &&
(board[r*n+c] != 0) && (board[r*n+c] != i))
return;
}
/* not a solution if piece in same / diagonal */
for (j = -n ; j < n ; j++) {
r = p / n + j;
c = p % n - j;
if ((r >= 0) && (r < n) && (c >= 0) && (c < n) &&
(board[r*n+c] != 0) && (board[r*n+c] != i))
return;
}
}
solutions++;
print_board();
}
/* move piece p to next position */
int next_pos(p)
{
int i, t;
if (p < 1)
return 0;
i = piece(p);
if (i < nsq-n+p-1) {
board[i] = 0;
board[i+1] = p;
return 1;
} else {
t = next_pos(p-1);
board[i] = 0;
board[piece(p-1)+1] = p;
return t;
}
}
/* generate the next possible solution */
int next_board()
{
return next_pos(n);
}
int main()
{
int i;
solutions = 0;
n = 5;
nsq = n*n; /* save n^2 to avoid calculating it again */
printf("\n\n\n\nSOLVING N QUEENS PROBLEM FOR N = %d\n", n);
/* clear the board */
for (i = 0 ; i < nsq ; i++)
board[i] = 0;
/* initially place the queens */
for (i = 0 ; i < n ; i++)
board[i] = i+1;
do {
tries++;
check_board();
} while (next_board());
printf("FOUND %d SOLUTIONS AFTER %ld TRIES.\n", solutions, tries);
return 0;
}
B>nqueens
SOLVING N QUEENS PROBLEM FOR N = 5
+---------------+
| Q . . . . |
| . . Q . . |
| . . . . Q |
| . Q . . . |
| . . . Q . |
+---------------+
+---------------+
| Q . . . . |
| . . . Q . |
| . Q . . . |
| . . . . Q |
| . . Q . . |
+---------------+
+---------------+
| . Q . . . |
| . . . Q . |
| Q . . . . |
| . . Q . . |
| . . . . Q |
+---------------+
+---------------+
| . Q . . . |
| . . . . Q |
| . . Q . . |
| Q . . . . |
| . . . Q . |
+---------------+
+---------------+
| . . Q . . |
| Q . . . . |
| . . . Q . |
| . Q . . . |
| . . . . Q |
+---------------+
+---------------+
| . . Q . . |
| . . . . Q |
| . Q . . . |
| . . . Q . |
| Q . . . . |
+---------------+
+---------------+
| . . . Q . |
| Q . . . . |
| . . Q . . |
| . . . . Q |
| . Q . . . |
+---------------+
+---------------+
| . . . Q . |
| . Q . . . |
| . . . . Q |
| . . Q . . |
| Q . . . . |
+---------------+
+---------------+
| . . . . Q |
| . Q . . . |
| . . . Q . |
| Q . . . . |
| . . Q . . |
+---------------+
+---------------+
| . . . . Q |
| . . Q . . |
| Q . . . . |
| . . . Q . |
| . Q . . . |
+---------------+
FOUND 10 SOLUTIONS AFTER -12406 TRIES.
B>
