+# Overview #
+
+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`. This also means
+`cpp` syntax must be respected.
+
# Reservations #
+Since all labels share a global namespace, the standard library makes the
+following 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 ##
+## 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 the block
+heap[1]-heap[15] by the stack rotation subroutines which time-share
+pseudo-registers between the various stdlib subroutines.
- The first 256 heap addresses are reserved when using the stdlib.
+By convention, functions which return a pointer will use the address `0` to
+represent a `NULL` pointer.
# Entry Points #
The following labels are entry points to stdlib functions. Read the
header comment for each function to learn the call and return stack.
- stdio.pvvs:
- 1000 - print string from stack
- 1001 - print string from heap
+ 000xxx - reserved
+ 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)
+ 10010 ----- greatest common divisor (math.pvvs)
+ 011xxx - heap functions
+ 11000 ----- memset (heap.pvvs)
+ 11001 ----- memcpy (heap.pvvs)
+ 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)
+ 100001 ----- isdigit (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
+ 110000 ----- atoi (convert.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 ----- lowbitand (logic.pvvs)
+ 1000001 ----- <empty>
+ 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 #
-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.