tools: add memdumpb

In C this time. Python/Perl code is barely terser than C for these little
tools. Why bother with interpreted?

tools/.gitignore

@@ -0,0 +1 @@
+/memdumpb

tools/Makefile

@@ -0,0 +1,13 @@
+CFLAGS ?= -Wall
+
+MEMDUMP_TGT = memdumpb
+MEMDUMP_SRC = memdump.c
+
+all: ${MEMDUMP_TGT}
+
+${MEMDUMP_TGT}: ${MEMDUMP_SRC}
+	${CC} ${CFLAGS} ${MEMDUMP_SRC} -o ${MEMDUMP_TGT}
+
+.PHONY: clean
+clean:
+	rm -f ${MEMDUMP_TGT}

tools/memdump.c

@@ -0,0 +1,68 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+/* Read specified number of bytes at specified memory address through a BASIC
+ * remote shell and dump it to stdout.
+ */
+
+void sendcmd(int fd, char *cmd)
+{
+    char junk[2];
+    while (*cmd) {
+        write(fd, cmd, 1);
+        read(fd, &junk, 1);
+        cmd++;
+        // The other side is sometimes much slower than us and if we don't let
+        // it breathe, it can choke.
+        usleep(1000);
+    }
+    write(fd, "\n", 1);
+    read(fd, &junk, 2); // sends back \r\n
+    usleep(1000);
+}
+
+int main(int argc, char **argv)
+{
+    if (argc != 4) {
+        fprintf(stderr, "Usage: ./memdump device memptr bytecount\n");
+        return 1;
+    }
+    unsigned int memptr = strtol(argv[2], NULL, 16);
+    unsigned int bytecount = strtol(argv[3], NULL, 16);
+    fprintf(stderr, "memptr: 0x%04x bytecount: 0x%04x.\n", memptr, bytecount);
+    if (memptr+bytecount > 0xffff) {
+        fprintf(stderr, "memptr+bytecount out of range.\n");
+        return 1;
+    }
+    if (!bytecount) {
+        // nothing to spit
+        return 0;
+    }
+
+    int fd = open(argv[1], O_RDWR|O_NOCTTY);
+    char s[0x20];
+    sprintf(s, "m=0x%04x", memptr);
+    sendcmd(fd, s);
+    read(fd, s, 2); // read prompt
+
+    for (int i=0; i<bytecount; i++) {
+        sendcmd(fd, "peek m");
+        read(fd, s, 2); // read prompt
+        sendcmd(fd, "print a");
+        for (int j=0; j<3; j++) {
+            read(fd, s+j, 1);
+            s[j+1] = 0; // always null-terminate
+            if (s[j] < '0') {
+                break;
+            }
+        }
+        unsigned char c = strtol(s, NULL, 10);
+        putchar(c);
+        read(fd, s, 3); // read \r\n + prompt - last char
+        sendcmd(fd, "m=m+1");
+        read(fd, s, 2); // read prompt
+    }
+    return 0;
+}