Moved legacy code into archive, ready for a new rapid(?) prototype.
I may regret doing this!
This commit is contained in:
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09051a3e63
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114 changed files with 165 additions and 1 deletions
508
archive/c/arith/integer.c
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508
archive/c/arith/integer.c
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/*
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* integer.c
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*
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* functions for integer cells.
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*
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* (c) 2017 Simon Brooke <simon@journeyman.cc>
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* Licensed under GPL version 2.0, or, at your option, any later version.
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*/
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#define _GNU_SOURCE
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#include <limits.h>
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#include <math.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <inttypes.h>
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/*
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* wide characters
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*/
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#include <wchar.h>
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#include <wctype.h>
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#include "arith/integer.h"
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#include "arith/peano.h"
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#include "debug.h"
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#include "memory/conspage.h"
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#include "memory/consspaceobject.h"
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#include "ops/equal.h"
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#include "ops/lispops.h"
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/**
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* hexadecimal digits for printing numbers.
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*/
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const char *hex_digits = "0123456789ABCDEF";
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/*
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* Doctrine from here on in is that ALL integers are bignums, it's just
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* that integers less than 61 bits are bignums of one cell only.
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* that integers less than 61 bits are bignums of one cell only.
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* TODO: why do I not have confidence to make this 64 bits?
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*/
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/*
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* A small_int_cache array of pointers to the integers 0...23,
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* used only by functions `acquire_integer(int64) => cons_pointer` and
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* `release_integer(cons_pointer) => NULL` which, if the value desired is
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* in the cache, supplies it from the cache, and, otherwise, calls
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* make_integer() and dec_ref() respectively.
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*/
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#define SMALL_INT_LIMIT 24
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bool small_int_cache_initialised = false;
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struct cons_pointer small_int_cache[SMALL_INT_LIMIT];
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/**
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* Low level integer arithmetic, do not use elsewhere.
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*
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* @param c a pointer to a cell, assumed to be an integer cell;
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* @param op a character representing the operation: expected to be either
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* '+' or '*'; behaviour with other values is undefined.
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* @param is_first_cell true if this is the first cell in a bignum
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* chain, else false.
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* \see multiply_integers
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* \see add_integers
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*/
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__int128_t cell_value( struct cons_pointer c, char op, bool is_first_cell ) {
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long int val = nilp( c ) ? 0 : pointer2cell( c ).payload.integer.value;
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long int carry = is_first_cell ? 0 : ( INT_CELL_BASE );
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__int128_t result = ( __int128_t ) integerp( c ) ?
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( val == 0 ) ? carry : val : op == '*' ? 1 : 0;
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debug_printf( DEBUG_ARITH,
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L"cell_value: raw value is %ld, is_first_cell = %s; '%4.4s'; returning ",
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val, is_first_cell ? "true" : "false",
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pointer2cell( c ).tag.bytes );
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debug_print_128bit( result, DEBUG_ARITH );
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debug_println( DEBUG_ARITH );
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return result;
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}
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/**
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* Allocate an integer cell representing this `value` and return a cons_pointer to it.
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* @param value an integer value;
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* @param more `NIL`, or a pointer to the more significant cell(s) of this number.
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* *NOTE* that if `more` is not `NIL`, `value` *must not* exceed `MAX_INTEGER`.
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*/
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struct cons_pointer make_integer( int64_t value, struct cons_pointer more ) {
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struct cons_pointer result = NIL;
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debug_print( L"Entering make_integer\n", DEBUG_ALLOC );
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if ( integerp( more )
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&& ( pointer2cell( more ).payload.integer.value < 0 ) ) {
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printf( "WARNING: negative value %" PRId64
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" passed as `more` to `make_integer`\n",
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pointer2cell( more ).payload.integer.value );
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}
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if ( integerp( more ) || nilp( more ) ) {
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result = allocate_cell( INTEGERTV );
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struct cons_space_object *cell = &pointer2cell( result );
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cell->payload.integer.value = value;
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cell->payload.integer.more = more;
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}
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debug_print( L"make_integer: returning\n", DEBUG_ALLOC );
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debug_dump_object( result, DEBUG_ALLOC );
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return result;
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}
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/**
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* @brief Supply small valued integers from the small integer cache, if available.
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*
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* The pattern here is intended to be that, at least within this file, instead of
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* calling make_integer when an integer is required and dec_ref when it's no longer
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* required, we call acquire_integer and release_integer respectively, in order to
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* reduce allocation churn.
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*
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* In the initial implementation, acquire_integer supplies the integer from the
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* small integer cache if available, else calls make_integer. Later, more
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* sophisticated caching of integers which are currently in play may be enabled.
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*
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* @param value the value of the integer desired.
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* @param more if this value is a bignum, the rest (less significant bits) of the
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* value.
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* @return struct cons_pointer a pointer to the integer acquired.
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*/
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struct cons_pointer acquire_integer( int64_t value, struct cons_pointer more ) {
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struct cons_pointer result;
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if ( !nilp( more ) || value < 0 || value >= SMALL_INT_LIMIT ) {
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debug_print
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( L"acquire_integer passing to make_integer (outside small int range)\n",
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DEBUG_ALLOC );
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result = make_integer( value, more );
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} else {
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if ( !small_int_cache_initialised ) {
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for ( int64_t i = 0; i < SMALL_INT_LIMIT; i++ ) {
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small_int_cache[i] = make_integer( i, NIL );
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pointer2cell( small_int_cache[i] ).count = MAXREFERENCE; // lock it in so it can't be GC'd
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}
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small_int_cache_initialised = true;
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debug_print( L"small_int_cache initialised.\n", DEBUG_ALLOC );
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}
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debug_printf( DEBUG_ALLOC, L"acquire_integer: returning %" PRId64 "\n",
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value );
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result = small_int_cache[value];
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}
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return result;
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}
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/**
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* @brief if the value of p is less than the size of the small integer cache
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* (and thus it was presumably supplied from there), suppress dec_ref.
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*
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* **NOTE THAT** at this stage it's still safe to dec_ref an arbitrary integer,
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* because those in the cache are locked and can't be dec_refed.
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*
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* @param p a pointer, expected to be to an integer.
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*/
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void release_integer( struct cons_pointer p ) {
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struct cons_space_object o = pointer2cell( p );
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if ( !integerp( p ) || // what I've been passed isn't an integer;
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!nilp( o.payload.integer.more ) || // or it's a bignum;
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o.payload.integer.value >= SMALL_INT_LIMIT || // or it's bigger than the small int cache limit;
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!eq( p, small_int_cache[o.payload.integer.value] ) // or it's simply not the copy in the cache...
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) {
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dec_ref( p );
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} else {
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debug_printf( DEBUG_ALLOC, L"release_integer: releasing %" PRId64 "\n",
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o.payload.integer.value );
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}
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}
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/**
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* @brief Overwrite the value field of the integer indicated by `new` with
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* the least significant INTEGER_BITS bits of `val`, and return the
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* more significant bits (if any) right-shifted by INTEGER_BITS places.
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*
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* Destructive, primitive, DO NOT USE in any context except primitive
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* operations on integers. The value passed as `new` MUST be constructed
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* with `make_integer`, NOT acquired with `acquire_integer`.
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*
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* @param val the value to represent;
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* @param less_significant the less significant words of this bignum, if any,
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* else NIL;
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* @param new a newly created integer, which will be destructively changed.
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* @return carry, if any, else 0.
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*/
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__int128_t int128_to_integer( __int128_t val,
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struct cons_pointer less_significant,
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struct cons_pointer new ) {
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__int128_t carry = 0;
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if ( MAX_INTEGER >= val ) {
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carry = 0;
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} else {
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carry = val % INT_CELL_BASE;
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debug_printf( DEBUG_ARITH,
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L"int128_to_integer: 64 bit overflow; setting carry to %ld\n",
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( int64_t ) carry );
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val /= INT_CELL_BASE;
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}
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struct cons_space_object *newc = &pointer2cell( new );
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newc->payload.integer.value = ( int64_t ) val;
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if ( integerp( less_significant ) ) {
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struct cons_space_object *lsc = &pointer2cell( less_significant );
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// inc_ref( new );
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lsc->payload.integer.more = new;
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}
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return carry;
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}
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/**
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* Return a pointer to an integer representing the sum of the integers
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* pointed to by `a` and `b`. If either isn't an integer, will return nil.
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*/
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struct cons_pointer add_integers( struct cons_pointer a,
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struct cons_pointer b ) {
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struct cons_pointer result = NIL;
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struct cons_pointer cursor = NIL;
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__int128_t carry = 0;
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bool is_first_cell = true;
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while ( integerp( a ) || integerp( b ) || carry != 0 ) {
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__int128_t av = cell_value( a, '+', is_first_cell );
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__int128_t bv = cell_value( b, '+', is_first_cell );
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__int128_t rv = ( av + bv ) + carry;
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debug_print( L"add_integers: av = ", DEBUG_ARITH );
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debug_print_128bit( av, DEBUG_ARITH );
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debug_print( L"; bv = ", DEBUG_ARITH );
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debug_print_128bit( bv, DEBUG_ARITH );
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debug_print( L"; carry = ", DEBUG_ARITH );
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debug_print_128bit( carry, DEBUG_ARITH );
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debug_print( L"; rv = ", DEBUG_ARITH );
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debug_print_128bit( rv, DEBUG_ARITH );
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debug_print( L"\n", DEBUG_ARITH );
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if ( carry == 0 && rv >= 0 && rv < SMALL_INT_LIMIT && is_first_cell ) {
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result = acquire_integer( ( int64_t ) ( rv & MAX_INTEGER ), NIL );
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break;
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} else {
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struct cons_pointer new = make_integer( 0, NIL );
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carry = int128_to_integer( rv, cursor, new );
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cursor = new;
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if ( nilp( result ) ) {
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result = cursor;
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}
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a = pointer2cell( a ).payload.integer.more;
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b = pointer2cell( b ).payload.integer.more;
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is_first_cell = false;
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}
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}
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debug_print( L"add_integers returning: ", DEBUG_ARITH );
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debug_print_object( result, DEBUG_ARITH );
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debug_println( DEBUG_ARITH );
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return result;
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}
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// TODO: I have really no idea what I was trying to do here, or why it could possibly be a good idea.
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struct cons_pointer base_partial( int depth ) {
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struct cons_pointer result = NIL;
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debug_printf( DEBUG_ARITH, L"base_partial: depth = %d\n", depth );
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for ( int i = 0; i < depth; i++ ) {
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result = acquire_integer( 0, result );
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}
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return result;
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}
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/**
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* @brief Return a copy of this `partial` with this `digit` appended.
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*
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* @param partial the more significant bits of a possible bignum.
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* @param digit the less significant bits of that possible bignum. NOTE: the
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* name `digit` is technically correct but possibly misleading, because the
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* numbering system here is base INT_CELL_BASE, currently x0fffffffffffffffL
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*/
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struct cons_pointer append_cell( struct cons_pointer partial,
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struct cons_pointer digit ) {
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struct cons_space_object cell = pointer2cell( partial );
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// TODO: I should recursively copy the whole bignum chain, because
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// we're still destructively modifying the end of it.
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struct cons_pointer c = make_integer( cell.payload.integer.value,
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cell.payload.integer.more );
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struct cons_pointer result = partial;
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if ( nilp( partial ) ) {
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result = digit;
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} else {
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// find the last digit in the chain...
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while ( !nilp( pointer2cell( c ).payload.integer.more ) ) {
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c = pointer2cell( c ).payload.integer.more;
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}
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( pointer2cell( c ) ).payload.integer.more = digit;
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}
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return result;
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}
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/**
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* Return a pointer to an integer representing the product of the integers
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* pointed to by `a` and `b`. If either isn't an integer, will return nil.
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*
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* Yes, this is one of Muhammad ibn Musa al-Khwarizmi's original recipes, so
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* you'd think it would be easy; the reason that each step is documented is
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* because I did not find it so.
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*
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* @param a an integer;
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* @param b an integer.
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*/
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struct cons_pointer multiply_integers( struct cons_pointer a,
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struct cons_pointer b ) {
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struct cons_pointer result = acquire_integer( 0, NIL );
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bool neg = is_negative( a ) != is_negative( b );
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bool is_first_b = true;
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int i = 0;
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debug_print( L"multiply_integers: a = ", DEBUG_ARITH );
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debug_print_object( a, DEBUG_ARITH );
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debug_print( L"; b = ", DEBUG_ARITH );
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debug_print_object( b, DEBUG_ARITH );
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debug_println( DEBUG_ARITH );
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if ( integerp( a ) && integerp( b ) ) {
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/* for each digit in a, starting with the least significant (ai) */
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for ( struct cons_pointer ai = a; !nilp( ai );
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ai = pointer2cell( ai ).payload.integer.more ) {
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/* set carry to 0 */
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__int128_t carry = 0;
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/* set least significant digits for result ri for this iteration
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* to i zeros */
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struct cons_pointer ri = base_partial( i++ );
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/* for each digit in b, starting with the least significant (bj) */
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for ( struct cons_pointer bj = b; !nilp( bj );
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bj = pointer2cell( bj ).payload.integer.more ) {
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debug_printf( DEBUG_ARITH,
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L"multiply_integers: a[i] = %Ld, b[j] = %Ld, i = %d\n",
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pointer2cell( ai ).payload.integer.value,
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pointer2cell( bj ).payload.integer.value, i );
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/* multiply ai with bj and add the carry, resulting in a
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* value xj which may exceed one digit */
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__int128_t xj = pointer2cell( ai ).payload.integer.value *
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pointer2cell( bj ).payload.integer.value;
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xj += carry;
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/* if xj exceeds one digit, break it into the digit dj and
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* the carry */
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carry = xj >> INTEGER_BIT_SHIFT;
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struct cons_pointer dj =
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acquire_integer( xj & MAX_INTEGER, NIL );
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replace_integer_p( ri, append_cell( ri, dj ) );
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// struct cons_pointer new_ri = append_cell( ri, dj );
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// release_integer( ri);
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// ri = new_ri;
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} /* end for bj */
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/* if carry is not equal to zero, append it as a final cell
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* to ri */
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if ( carry != 0 ) {
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replace_integer_i( ri, carry )
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}
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/* add ri to result */
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result = add_integers( result, ri );
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debug_print( L"multiply_integers: result is ", DEBUG_ARITH );
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debug_print_object( result, DEBUG_ARITH );
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debug_println( DEBUG_ARITH );
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} /* end for ai */
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}
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debug_print( L"multiply_integers returning: ", DEBUG_ARITH );
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debug_print_object( result, DEBUG_ARITH );
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debug_println( DEBUG_ARITH );
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return result;
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}
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/**
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* don't use; private to integer_to_string, and somewhat dodgy.
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*/
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struct cons_pointer integer_to_string_add_digit( int digit, int digits,
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struct cons_pointer tail ) {
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wint_t character = btowc( hex_digits[digit] );
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debug_printf( DEBUG_IO,
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L"integer_to_string_add_digit: digit is %d, digits is %d; returning: ",
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digit, digits );
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struct cons_pointer r =
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( digits % 3 == 0 ) ? make_string( L',', make_string( character,
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tail ) ) :
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make_string( character, tail );
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debug_print_object( r, DEBUG_IO );
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debug_println( DEBUG_IO );
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return r;
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}
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/**
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* @brief return a string representation of this integer, which may be a
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* bignum.
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*
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* The general principle of printing a bignum is that you print the least
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* significant digit in whatever base you're dealing with, divide through
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* by the base, print the next, and carry on until you've none left.
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* Obviously, that means you print from right to left. Given that we build
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* strings from right to left, 'printing' an integer to a lisp string
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* would seem reasonably easy. The problem is when you jump from one integer
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* object to the next. 64 bit integers don't align with decimal numbers, so
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* when we get to the last digit from one integer cell, we have potentially
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* to be looking to the next. H'mmmm.
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*
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* @param int_pointer cons_pointer to the integer to print,
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* @param base the base to print it in.
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*/
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struct cons_pointer integer_to_string( struct cons_pointer int_pointer,
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int base ) {
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struct cons_pointer result = NIL;
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if ( integerp( int_pointer ) ) {
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struct cons_pointer next =
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pointer2cell( int_pointer ).payload.integer.more;
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__int128_t accumulator =
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llabs( pointer2cell( int_pointer ).payload.integer.value );
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bool is_negative =
|
||||
pointer2cell( int_pointer ).payload.integer.value < 0;
|
||||
int digits = 0;
|
||||
|
||||
if ( accumulator == 0 && nilp( next ) ) {
|
||||
result = c_string_to_lisp_string( L"0" );
|
||||
} else {
|
||||
while ( accumulator > 0 || !nilp( next ) ) {
|
||||
if ( accumulator < MAX_INTEGER && !nilp( next ) ) {
|
||||
accumulator +=
|
||||
( pointer2cell( next ).payload.integer.value %
|
||||
INT_CELL_BASE );
|
||||
next = pointer2cell( next ).payload.integer.more;
|
||||
}
|
||||
int offset = ( int ) ( accumulator % base );
|
||||
debug_printf( DEBUG_IO,
|
||||
L"integer_to_string: digit is %ld, hexadecimal is %c, accumulator is: ",
|
||||
offset, hex_digits[offset] );
|
||||
debug_print_128bit( accumulator, DEBUG_IO );
|
||||
debug_print( L"; result is: ", DEBUG_IO );
|
||||
debug_print_object( result, DEBUG_IO );
|
||||
debug_println( DEBUG_IO );
|
||||
|
||||
result =
|
||||
integer_to_string_add_digit( offset, ++digits, result );
|
||||
accumulator = accumulator / base;
|
||||
}
|
||||
|
||||
if ( stringp( result )
|
||||
&& pointer2cell( result ).payload.string.character == L',' ) {
|
||||
/* if the number of digits in the string is divisible by 3, there will be
|
||||
* an unwanted comma on the front. */
|
||||
result = pointer2cell( result ).payload.string.cdr;
|
||||
}
|
||||
|
||||
|
||||
if ( is_negative ) {
|
||||
result = make_string( L'-', result );
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
return result;
|
||||
}
|
||||
|
||||
/**
|
||||
* true if a and be are both integers whose value is the same value.
|
||||
*/
|
||||
bool equal_integer_integer( struct cons_pointer a, struct cons_pointer b ) {
|
||||
bool result = false;
|
||||
|
||||
if ( integerp( a ) && integerp( b ) ) {
|
||||
struct cons_space_object *cell_a = &pointer2cell( a );
|
||||
struct cons_space_object *cell_b = &pointer2cell( b );
|
||||
|
||||
result =
|
||||
cell_a->payload.integer.value == cell_b->payload.integer.value;
|
||||
}
|
||||
|
||||
return result;
|
||||
}
|
||||
Loading…
Add table
Add a link
Reference in a new issue