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 intval_mod(INTVAL i2, INTVAL i3): 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 floatval_mod(FLOATVAL n2, FLOATVAL n3): 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.

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

Array Functions

void *Parrot_make_la(Interp *interp, PMC *array): 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.
void Parrot_destroy_la(long *array): Use this to destroy an array created with Parrot_make_la().
void *Parrot_make_cpa(Interp *interp, PMC *array): 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.
void Parrot_destroy_cpa(char **array): Use this to destroy an array created with Parrot_make_cpa().
PMC *tm_to_array(Parrot_Interp, struct tm *): Helper to convert a struct tm * to an Array
void rec_climb_back_and_mark(int node_index, parrot_prm_context *c): 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.
void process_cycle_without_exit(int node_index, parrot_prm_context *c): 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
typedef int (*reg_move_func)(Interp*, unsigned char d, unsigned char s, void *);
void Parrot_register_move(Interp *, int n_regs, unsigned char *dest_regs, unsigned char *src_regs, unsigned char temp_reg, reg_move_func mov, reg_move_func mov_alt, void *info): Move n_regs from the given register list src_regs to dest_regs.; Some dest_regs might be the same as src_regs, which makes this a bit non-trivial, because if the destination is already clobbered, using it later as source doesn"t work. E.g.; or; To handle such cases, we do:; The amount of register moves should of course be minimal.; TODO The current implementation will not work for following cases; Talked to Leo and he said those cases are not likely (Vishal Soni). 1. I0->I1 I1->I0 I0->I3 2. I1->I2 I3->I2; TODO: Add tests for the above conditions.

HISTORY

Initial version by leo 2003.09.09.