tools: wc, head, and an argc/argv demo (args) + libc.c helpers

- c/libc.c: shared C helpers linked into every program - putu (print decimal),
  atou (parse decimal), argv_parse (tokenize getargs() into argc/argv).
- wc: count lines/words/chars of stdin. head [n]: first n lines (drains rest to
  EOF). args: argc/argv demo.
- pid now uses libc putu; build.sh links libc.c; Makefile CBLOBS + libc dep.
- README: document the new tools + argv_parse.
- verified: 'args one two three' -> argc=3/argv[..]; wc '2 3 16'; head 2.

1 files changed, 12 insertions, 0 deletions

diff --git a/c/args.c b/c/args.c
new file mode 100644
index 0000000..c6f4db3
--- /dev/null
+++ b/c/args.c
@@ -0,0 +1,12 @@
+#include "gbos.h"
+/* args: an argc/argv demo. Splits its argument string into argv[] and prints
+   argc plus each argument. Try: `args one two three` */
+void main(void) {
+    char *argv[8];
+    unsigned char argc = argv_parse(argv, 8);
+    unsigned char i;
+    puts("argc="); putu(argc); nl();
+    for (i = 0; i < argc; i++) {
+        puts("argv["); putu(i); puts("]="); puts(argv[i]); nl();
+    }
+}