simon/post-scarcity
1
0
Fork 0
Code Issues 14 Pull requests Projects Releases Packages Wiki Activity Actions

Upversioned the C source tree to '0.0.7-SNAPSHOT', but proposing to start experimental

Browse source 
work towards 0.1.0 in separate source trees.
This commit is contained in:
Simon Brooke 2026-03-19 13:59:06 +00:00
parent 788cb48b37
commit 99d4794f3b
57 changed files with 2 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

508
src/arith/integer.c
View file

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