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/*
Copyright (c) 2006 Stig Brautaset. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
Neither the name of the author nor the names of its contributors may be used
to endorse or promote products derived from this software without specific
prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <string.h>
/* I need a fast, unsigned, 32-bit integer type. C99's got just the thing. */
#include <stdint.h>
typedef uint_fast32_t um_uint;
/* we need to know the length of a platter array to duplicate it */
typedef struct {
size_t len;
um_uint content[];
} um_array;
/* allows us to store a list of indices that can be reused */
typedef struct _um_freelist {
struct _um_freelist *next;
size_t idx;
} um_freelist;
/* we need to store lengths of collections */
struct um {
size_t pc, /* program counter ("finger") */
len, /* length of parent array */
next; /* next slot for platter array */
um_uint reg[8]; /* UM registers */
um_array **parr; /* collection of platter arrays */
um_freelist *free; /* free list; holds indices into parr that can be reused */
};
/* create a node for the freelist */
static inline um_freelist *um_freelist_push(um_freelist *p, um_uint n)
{
um_freelist *l = calloc(sizeof(um_freelist), 1);
assert(l != NULL);
l->idx = n;
if (p)
l->next = p;
return l;
}
/* creates a platter array of the given size */
static inline um_array *um_mkarray(size_t size)
{
um_array *p = calloc(size * sizeof(um_uint) + sizeof(um_array), 1);
p->len = size;
return p;
}
/* read in the program from a file */
static um_array *um_read_scroll(char *name)
{
um_array *arr;
assert(name != NULL);
assert(*name); /* non-empty string */
{
int i, len, c;
FILE *fp = fopen(name, "r");
assert(fp != NULL);
/* find length of file */
for (len = 0; EOF != getc(fp); len++)
;
/* allocate array 'big enough' */
arr = um_mkarray(len / 4 + 1);
rewind(fp);
/* read bytestream and write into array at correct location */
for (i = 0; (c = getc(fp)) != EOF; i++) {
assert(c <= 255);
assert(c >= 0);
arr->content[ i / 4 ] <<= 8;
arr->content[ i / 4 ] += c;
}
/* make sure the last is shifted correctly */
arr->content[ i / 4] <<= (i % 4) * 8;
assert(len == i);
}
return arr;
}
/* operators are found in the high nibble */
#define OP(n) (n >> 28)
/* extract segment values */
#define SEGC(n) (n & 07) /* segment C */
#define SEGB(n) ((n >> 3) & 07) /* segment B */
#define SEGA(n) ((n >> 6) & 07) /* segment A */
#define REGA um->reg[SEGA(p)]
#define REGB um->reg[SEGB(p)]
#define REGC um->reg[SEGC(p)]
/* op 13 is different from the others */
#define OP13SEG(n) ((n & 0xe000000) >> 25) /* segment A */
#define OP13VAL(n) (n & 0x1ffffff) /* value */
/* run loop */
static int um_run(struct um *um)
{
for (;;) {
um_uint p = um->parr[0]->content[um->pc++];
switch (OP(p)) {
case 0: /* Conditional Move. */
if (REGC) {
REGA = REGB;
}
break;
case 1: /* Array Index. */
REGA = um->parr[ REGB ]->content[ REGC ];
break;
case 2: /* Array Amendment. */
um->parr[ REGA ]->content[ REGB ] = REGC;
break;
case 3: /* Addition. */
REGA = REGB + REGC;
break;
case 4: /* Multiplication. */
REGA = REGB * REGC;
break;
case 5: /* Division. */
assert(REGC);
REGA = REGB / REGC;
break;
case 6: /* Not-And. */
REGA = ~(REGB & REGC);
break;
case 7: /* Halt. */
for (um_freelist *l; l = um->free; free(l))
um->free = l->next;
free(um->parr);
return 0;
break;
case 8: /* Allocation. */
{
um_uint idx;
if (um->free) {
um_freelist *l = um->free;
um->free = l->next;
idx = l->idx;
free(l);
}
else {
if (++um->next == um->len) {
um->len *= 2;
um->parr = realloc(um->parr, um->len * sizeof(um_uint*));
}
idx = um->next;
}
um->parr[ idx ] = um_mkarray( REGC );
REGB = idx;
}
break;
case 9: /* Abandonment. */
free(um->parr[ REGC ]);
um->free = um_freelist_push( um->free, REGC );
break;
case 10: /* Output. */
assert(REGC <= 255);
putchar(REGC);
break;
case 11: /* Input. */
{
int c = getchar();
REGC = c == EOF ? ~0 : c;
}
break;
case 12: /* Load Program. */
if (REGB) {
free(um->parr[0]);
um->parr[0] = um_mkarray( um->parr[ REGB ]->len );
memmove(um->parr[ 0 ],
um->parr[ REGB ],
um->parr[ REGB ]->len * sizeof(um_uint) + sizeof(um_array));
}
um->pc = REGC;
break;
case 13: /* Orthography. (SET) */
um->reg[ OP13SEG(p) ] = OP13VAL(p);
break;
default:
fprintf(stderr, "Illegal operator encounted: '%u'\n", OP(p));
return -1;
break;
}
}
}
int main(int argc, char **argv)
{
struct um um = { 0 };
um.len = 128; /* preallocate some memory */
um.parr = calloc(sizeof(um_uint*), um.len);
um.parr[0] = um_read_scroll(argv[1]);
if (!um_run(&um))
return 0;
return EXIT_FAILURE;
}