filesystem: a RAM FS (WRAMX) + ls/cat/save/rm; wc/head read files

- fs.asm: 8-slot RAM filesystem in WRAMX ($D000-$DFFF), name[8]+len[2]+data[502];
  syscalls open/close/getb/putb/list/remove, seeded with a 'readme' at boot.
- libc: open/close/fgetc/fputc/flist/fremove wrappers + O_READ/O_WRITE/NOFD.
- tools: ls, save (stdin->file, one line), rm; cat/wc/head now take a file arg.
- fix: syscall dispatch clobbers A, so putb takes its byte in E (was reading the
  handler's low address byte, 0xDC); ls NUL-terminates 8-char names.
- verified: save/cat/ls/rm cycle; wc readme -> '2 7 38'; head -n 1 readme.
- README: document the filesystem + the A-clobber ABI note.

1 files changed, 14 insertions, 7 deletions

diff --git a/c/wc.c b/c/wc.c
index 86c3aed..424876d 100644
--- a/c/wc.c
+++ b/c/wc.c
@@ -1,5 +1,5 @@
 #include "gbos.h"
-/* wc [-l] [-w] [-c]: count lines, words, chars of stdin (default: all). */
+/* wc [-l][-w][-c] [file]: count lines/words/chars of a file or stdin. */
 void main(void) {
     char *argv[8];
     unsigned char argc = argv_parse(argv, 8);
@@ -7,17 +7,24 @@ void main(void) {
     unsigned char ww = hasflag(argv, argc, 'w');
     unsigned char wch = hasflag(argv, argc, 'c');
     unsigned int lines = 0, words = 0, chars = 0;
-    unsigned char inword = 0, first = 1;
-    char c;
+    unsigned char inword = 0, first = 1, i, fd = NOFD;
+    char *fname = 0;
+    int ch;
     if (!wl && !ww && !wch) { wl = ww = wch = 1; }
+    for (i = 0; i < argc; i++) if (argv[i][0] != '-') { fname = argv[i]; break; }
+    if (fname) {
+        fd = open(fname, O_READ);
+        if (fd == NOFD) { puts("wc: no such file"); nl(); return; }
+    }
     for (;;) {
-        c = readc();
-        if (c == EOF) break;
+        if (fd == NOFD) { char c = readc(); if (c == EOF) break; ch = c; }
+        else { ch = fgetc(fd); if (ch < 0) break; }
         chars++;
-        if (c == '\n') lines++;
-        if (c == ' ' || c == '\n' || c == '\r' || c == '\t') inword = 0;
+        if (ch == '\n') lines++;
+        if (ch == ' ' || ch == '\n' || ch == '\r' || ch == '\t') inword = 0;
         else if (!inword) { inword = 1; words++; }
     }
+    if (fd != NOFD) close(fd);
     if (wl)  { putu(lines); first = 0; }
     if (ww)  { if (!first) putc(' '); putu(words); first = 0; }
     if (wch) { if (!first) putc(' '); putu(chars); }