Add docblock comments

src/apple2.lores.c

@@ -91,6 +91,14 @@ apple2_lores_draw(apple2 *mach, size_t addr)
     vm_screen_draw_rect(mach->screen, &dest);
 }
 
+/*
+ * Return the color that corresponds to the value in the given byte.
+ * Even though we receive a byte, lores color data is stored two cells
+ * to a byte, so all we ever get here will be contained within the first
+ * four bits; therefore we mask the byte as we index the lores colors
+ * table, to ensure a bad value doesn't end up returning a value out of
+ * bounds.
+ */
 vm_color
 apple2_lores_color(vm_8bit byte)
 {

src/vm_segment.c

@@ -354,6 +354,13 @@ vm_segment_set16(vm_segment *segment, size_t addr, vm_16bit value)
     return err;
 }
 
+/*
+ * Print a hex dump of the region of memory between from and to into the
+ * given file stream. This looks vaguely like the output of the hexdump
+ * Unix command, except that the hex values are upper-case, and we use
+ * brackets instead of vertical bars to delimit the ASCII output because
+ * WHY NOT.
+ */
 void
 vm_segment_hexdump(vm_segment *seg, FILE *stream, size_t from, size_t to)
 {