refactor: c/ -> usr/, compiled program blobs out of the source tree

Userland sources live in usr/ (fits the Unix theme better than 'c').
SDCC output .bin blobs land in build/usr/ with the other build artifacts
instead of littering the source dir; programs.asm INCBINs them from there.
Byte-identical ROM.

1 files changed, 57 insertions, 0 deletions

diff --git a/usr/chat.c b/usr/chat.c
new file mode 100644
index 0000000..987b336
--- /dev/null
+++ b/usr/chat.c
@@ -0,0 +1,57 @@
+#include "netlib.h"
+/* chat: a link-port chat client. Incoming SLIP frames from the host gateway
+   print as messages; SELECT brings up the on-screen keyboard, type a line and
+   press START to send it. A poll loop interleaves receiving and typing so
+   messages arrive while you're not mid-line. */
+
+static char rxbuf[96];
+static unsigned char rxlen, rxin, rxesc;
+
+/* feed one non-blocking byte to the SLIP receiver; returns a frame length when
+   a whole frame has arrived (copied into out), else 0. */
+static unsigned char slip_poll(char *out) {
+    int b = srecv_nb();
+    unsigned char c, i, n;
+    if (b < 0) return 0;
+    c = (unsigned char)b;
+    if (c == SLIP_END) {
+        if (rxin && rxlen) {
+            n = rxlen;
+            for (i = 0; i < n; i++) out[i] = rxbuf[i];
+            rxlen = 0; rxin = 0; rxesc = 0;
+            return n;
+        }
+        rxin = 1; rxlen = 0; rxesc = 0;
+        return 0;
+    }
+    if (!rxin) return 0;
+    if (rxesc) {
+        if (c == SLIP_ESC_END) c = SLIP_END;
+        else if (c == SLIP_ESC_ESC) c = SLIP_ESC;
+        rxesc = 0;
+    } else if (c == SLIP_ESC) { rxesc = 1; return 0; }
+    if (rxlen < 96) rxbuf[rxlen++] = (char)c;
+    return 0;
+}
+
+void main(void) {
+    char line[64], frame[96];
+    unsigned char linelen = 0, n, i, c;
+    puts("chat: SELECT=keyboard  START=send"); nl();
+    for (;;) {
+        n = slip_poll(frame);              /* incoming message? */
+        if (n) {
+            for (i = 0; i < n; i++) putc(frame[i]);
+            nl();
+        }
+        c = pollin();                      /* typed a key? */
+        if (c == '\n') {
+            if (linelen) { slip_send(line, linelen); linelen = 0; }
+        } else if (c == 8) {
+            if (linelen) { linelen--; putc(8); }
+        } else if (c) {
+            if (linelen < 63) { line[linelen++] = (char)c; putc((char)c); }
+        }
+        yield();
+    }
+}