Update README.md.

README.md

@@ -1,7 +1,67 @@
-# dmm
+# DMM
 
-A memory management library made for
-[awooOS](https://github.com/awooos/awooos).
+A memory management library, made for [awooOS](https://github.com/awooos/awooos).
+
+DMM supports multiple simultaneous instances, allowing you to
+manage different sections of memory independently. It also provides a
+simpler API, if you wish to use a single instance.
+
+The multi-instance version isn't documented yet. (Sorry about that.)
+
+## Requirements
+
+1. A valid `stddef.h` and `stdint.h` (usually provided by libc).
+2. A "panic" function (see below).
+
+The panic function must have the following signature:
+
+```c
+void _panic(const char *message, const char *function,
+            const char *filename, size_t line);
+```
+
+## Basic Usage (global instance)
+
+If you want just a single DMM instance, you can do the
+following:
+
+```c
+#include <dmm.h>    // pulls in <stddef.h>
+#include <stdlib.h> // for exit()
+
+void _panic(const char *message, const char *function,
+            const char *filename, size_t line) {
+    // Loosely based on Rust's panic message format.
+    fprintf(stderr, "function '%s' panicked at '%s', %s:%zu\n", function, message, filename, line);
+    exit(1);
+}
+
+int main(void) {
+    char *region1 = malloc(10);
+    char *region2 = malloc(512);
+    char *region3 = malloc(1024);
+
+    dmm_init(&_panic);
+
+    dmm_add_memory_region(region1, 10);
+    dmm_add_memory_region(region2, 512);
+    dmm_add_memory_region(region3, 1024);
+
+    dmm_malloc(9);   // can be from any region
+    dmm_malloc(100); // can be from region2 or region3
+    dmm_malloc(600); // can only be from region3.
+
+    // Clean up after ourselves.
+    free(region1);
+    free(region2);
+
+    return 0;
+}
+```
+
+## Advanced Usage (multiple instances)
+
+TODO.
 
 # License