NAME

src/utils.c - Some utility functions

DESCRIPTION

Prototypes are in src/misc.h.

Opcode helper functions that don't really fit elsewhere.

Functions

intval_mod: NOTE: This "corrected mod" algorithm is based on the C code on page 70 of [1]. Assuming correct behavior of the built-in mod operator (%) with positive arguments, this algorithm implements a mathematically convenient version of mod, defined thus:; For more information on this definition of mod, see section 3.4 of [2], pages 81-85.; References:; [1] Donald E. Knuth, *MMIXware: A RISC Computer for the Third Millennium* Springer, 1999.; [2] Ronald L. Graham, Donald E. Knuth and Oren Patashnik, *Concrete Mathematics*, Second Edition. Addison-Wesley, 1994.
floatval_mod: Returns n2 mod n3.; Includes a workaround for buggy code generation in the lcc compiler.

Random Number Generator

Based on the rand48() family of functions.

next_rand: Returns the next random number in X.
_erand48: Returns a double in the interval [0.0, 1.0).
_drand48: Returns a double in the interval [0.0, 1.0).
_jrand48: Returns a long in the interval [-2^31, 2^31).
_nrand48: Returns a long in the interval [0, 2^31).
_lrand48: Returns a long in the interval [0, 2^31).
_mrand48: Returns a long in the interval [-2^31, 2^31).
_srand48: Sets the high order 32 bits to the argument seed. The low order 16 bits are set to the arbitrary value 0x330e.
Parrot_float_rand: Returns a FLOATVAL in the interval [0.0, 1.0).; how_random is ignored.
Parrot_uint_rand: Returns an INTVAL in the interval [0, 2^31).; how_random is ignored.
Parrot_int_rand: Returns an INTVAL in the interval [-2^31, 2^31).; how_random is ignored.
Parrot_range_rand: Returns an INTVAL in the range [from, to].; how_random is ignored.
Parrot_srand: Seeds the random number generator with seed.

Array Functions

Parrot_make_la: Creates a C array of longs with one more element than the number of elements in *array. The elements are then copied from *array to the new array, and the last (extra) element is set to 0.; Used in src/nci.c.
Parrot_destroy_la: Use this to destroy an array created with Parrot_make_la().
Parrot_make_cpa: Creates a C array of char *s with one more element than the number of elements in *array. The elements are then copied from *array to the new array, and the last (extra) element is set to 0.; Currently unused.; Note that you need to free this array with Parrot_destroy_cpa().
Parrot_destroy_cpa: Use this to destroy an array created with Parrot_make_cpa().
tm_to_array: Helper to convert a struct tm * to an Array
rec_climb_back_and_mark: Recursive function, used by Parrot_register_move to climb back the graph of register moves operations.; The node must have a predecessor: it is implicit because if a node has a node_index, it must have a predecessor because the node_index are the index of registers in dest_regs[] array, so by definition they have a corrsponding src_regs register.; Then it emits the move operation with its predecessor, or its backup if already used/visited.; Then continues the climbing if the predecessor was not modified, anf in that case marks it, and set node_index as its backup.
process_cycle_without_exit: Recursive function, used by Parrot_register_move to handle the case of cycles without exits, that are cycles of move ops between registers where each register has exactly one predecessor and one successor; For instance: 1-->2, 2-->3, 3-->1

HISTORY

Initial version by leo 2003.09.09.