0xxxxxxx xxxxxxxx - reserved for private use by stdlib
1xxxxxxx xxxxxxxx - available for use in user programs
-## Heap ##
+## Heap and Pointers ##
- The first 256 heap addresses are reserved when using the stdlib.
+The first 16 heap addresses (`0-15`) are reserved when using the stdlib.
+Within that reservation, heap[0] is used by `random` and the block
+heap[2]-heap[15] by the stack rotation subroutines which time-share these
+pseudo-registers between the various stdlib subroutines.
+
+By convention, functions which return a pointer will use the address `0` to
+represent a `NULL` pointer.
# Entry Points #
header comment for each function to learn the call and return stack.
000xxx - reserved
- 001xxx - print functions
- 1000 ----- print string from stack (stdio.pvvs)
- 1001 ----- print string from heap (stdio.pvvs)
- 1010 ----- print number from stack (stdio.pvvs)
+ 001xxx - core functions
+ 1000 ----- printf (stdio.pvvs)
+ 1001 ----- print number from stack (stdio.pvvs)
+ 1010 ----- stackrotate (stack.pvvs)
+ 1011 ----- stackrotatereverse (stack.pvvs)
+ 1100 ----- deepdup (stack.pvvs)
010xxx - math functions
10000 ----- random (math.pvvs)
10001 ----- absolute value (math.pvvs)
011xxx - heap functions
11000 ----- memset (heap.pvvs)
11001 ----- memcpy (heap.pvvs)
- 100xxx - unassigned
- 101xxx - unassigned
+ 11010 ----- memrand (heap.pvvs)
+ 11011 ----- memcmp (heap.pvvs)
+ 11100 ----- memsrch (heap.pvvs)
+ 11101 ----- <empty>
+ 11110 ----- slurp (heap.pvvs)
+ 11111 ----- spew (heap.pvvs)
+ 100xxx - string functions
+ 100000 ----- strlen (string.pvvs)
+ 101xxx - logic functions
+ 101000 ----- not (logic.pvvs)
+ 101001 ----- and (logic.pvvs)
+ 101010 ----- or (logic.pvvs)
+ 101011 ----- xor (logic.pvvs)
+ 101100 ----- rshift (logic.pvvs)
+ 101101 ----- lshift (logic.pvvs)
110xxx - conversion functions
111xxx - debug functions
111000 ----- dump heap (debug.pvvs)
+ 111001 ----- dump stack (debug.pvvs)
+ 111010 ----- print sign (debug.pvvs)
+ 111011 ----- print magnitude (debug.pvvs)
+ 111100 ----- print string (debug.pvvs)
1xxxxxx - reserved for less common entry points
- 1000000 ----- print sign of number (stdio.pvvs)
- 1000001 ----- print magnitude of number (stdio.pvvs)
+ 1000000 ----- lowbitand (logic.pvvs)
+ 1000001 ----- isnegative (math.pvvs)
+ 1000010 ----- print sign of number (stdio.pvvs)
+ 1000011 ----- print magnitude of number (stdio.pvvs)
+ 1000100 ----- print string from stack (stdio.pvvs)
+ 1000101 ----- print string from heap (stdio.pvvs)
# Misc #