This folder contains a library of useful functions written in VVhitespace.
Standard include guards are used with `cpp` to include the stdlib in user
-programs. For an example, see `examples/hello-stdlib`.
+programs. For an example, see `examples/hello-stdlib`. This also means
+`cpp` syntax must be respected.
# Reservations #
## Label ##
00000000 0xxxxxxx - reserved for stdlib function entry points
- 00000000 1xxxxxxx - unassigned
+ 00000000 1xxxxxxx - available for use in user programs
0xxxxxxx xxxxxxxx - reserved for private use by stdlib
1xxxxxxx xxxxxxxx - available for use in user programs
## 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.
+Within that reservation, heap[0] is used by `random` and the block
+heap[1]-heap[15] by the stack rotation subroutines which time-share
+pseudo-registers between the various stdlib subroutines.
By convention, functions which return a pointer will use the address `0` to
represent a `NULL` pointer.
010xxx - math functions
10000 ----- random (math.pvvs)
10001 ----- absolute value (math.pvvs)
+ 10010 ----- greatest common divisor (math.pvvs)
011xxx - heap functions
11000 ----- memset (heap.pvvs)
11001 ----- memcpy (heap.pvvs)
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)
+ 111101 ----- print signed number (debug.pvvs)
1xxxxxx - reserved for less common entry points
- 1000000 ----- <empty>
+ 1000000 ----- lowbitand (logic.pvvs)
1000001 ----- <empty>
1000010 ----- print sign of number (stdio.pvvs)
1000011 ----- print magnitude of number (stdio.pvvs)
# Misc #
-By convention, each public stdlib label will have 8 bits of
-private label space associated with it, formed as follows:
+## Private Label Space ##
+
+By convention, each public stdlib label will have 8 bits of private label space
+associated with it, formed as follows:
00001000 xxxxxxxx - for use by 1000
00001001 xxxxxxxx - for use by 1001
...etc
+
+## Extending Heap Reservation ##
+
+By default, the stdlib uses the first 16 heap addresses. All heap access (other
+than heap[0] as a seed) occurs through `stackrotate` and `stackrotatereverse`.
+Edit these functions to increase the stdlib's heap reservation.
+
+The remainder of the stdlib is written to automatically use the new allocation.
+Functions like `printf`, for example, allow more substitutions when the heap
+allocation is increased.