## Heap and Pointers ##
The first 16 heap addresses (`0-15`) are reserved when using the stdlib.
+Within that reservation, heap[0] is used by `random` and heap[15] is used
+by `spewreg`. The remaining 14 locations, heap[1]-heap[14] are used as
+general-purpose registers.
By convention, functions which return a pointer will use the address `0` to
represent a `NULL` pointer.
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)
010xxx - math functions
10000 ----- random (math.pvvs)
10001 ----- absolute value (math.pvvs)
11101 ----- <empty>
11110 ----- slurp (heap.pvvs)
11111 ----- spew (heap.pvvs)
- 100xxx - unassigned
+ 100xxx - string functions
+ 100000 ----- strlen (string.pvvs)
101xxx - unassigned
110xxx - conversion functions
111xxx - debug functions
111000 ----- dump heap (debug.pvvs)
+ 111001 ----- dump stack (debug.pvvs)
1xxxxxx - reserved for less common entry points
- 1000000 ----- print sign of number (stdio.pvvs)
- 1000001 ----- print magnitude of number (stdio.pvvs)
+ 1000000 ----- slurp registers (heap.pvvs)
+ 1000001 ----- spew registers (heap.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 #
00001000 xxxxxxxx - for use by 1000
00001001 xxxxxxxx - for use by 1001
...etc
-
-# Slurp and Spew #
-
-The stdlib uses heap[1] to heap[15] as registers.
-
-The `slurp` and `spew` functions facilitate this by `spew`ing the stack onto
-the heap's pseudo-registers or `slurp`ing the pseudo-registers back to the
-stack. The functions preserve order in complementary fashion.
-
-The `spew` function uses `heap[0]` for storage.