-
Notifications
You must be signed in to change notification settings - Fork 0
/
cell.h
118 lines (92 loc) · 3.85 KB
/
cell.h
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
/* MIX simulator, copyright 1994 by Darius Bacon */
#include "mix.h"
#ifndef CELL_H
#define CELL_H
/* --- Call this before anything else --- */
void precompute_field_data(void);
/*
* MIX values ---
*
* Currently represented as a long. (A long must have >= 31 bits.)
* Bit 30 is the sign, higher bits are 0, and bits 0-29 are the magnitude.
* (If we made the high bit the sign, would it be a little faster to check?)
* Each MIX 'byte' is a 6-bit substring of the magnitude.
*
* Other reps which might make sense:
* array of bytes
* pair (sign, magnitude)
* 1's-complement???
* (a kind of halfway house between 2's-complement and sign/magnitude)
* (alas, field operations would be more work...)
* Unfortunately, in several places I've made the convenient assumption that
* the magnitude of a MIX cell can be converted to a C long int; that would
* be wrong for, e.g., a decimal MIX machine if a long int is only 32 bits.
*/
typedef long Cell;
typedef unsigned Byte; /* 0..63 */
/* These are to allow symbol.c to convert a Cell to or from a unique string
representation. We could just as easily use unparse() if we defined a
complementary parse() function. */
#define cell_to_long(c) (c)
#define long_to_cell(l) (l)
/* Largest possible magnitude of a Cell */
#define CELL_MAX ((1L << 30) - 1)
/* Largest possible magnitude of an index register (i.e., 2 bytes) */
extern Cell INDEX_MAX;
#define zero ((Cell) 0)
#define the_sign_bit (1L << 30)
#define negative(cell) ( (cell) ^ the_sign_bit )
#define sign_bit(cell) ( (cell) & the_sign_bit )
#define magnitude(cell) ( (cell) & (the_sign_bit - 1) )
#define is_negative(cell) ( sign_bit(cell) != 0 )
Cell ulong_to_cell(unsigned long n);
Byte make_field_spec(unsigned L, unsigned R);
void assert_valid_field(Cell field_spec);
/*** should separate into fast/safe versions */
Cell field(Byte field_spec, Cell cell);
Cell set_field(Cell value, Byte field_spec, Cell into);
Byte get_byte(unsigned field, Cell cell);
Cell set_byte(Byte value, unsigned field, Cell into);
extern Flag overflow;
Cell add(Cell x, Cell y);
Cell sub(Cell x, Cell y);
void multiply(Cell x, Cell y, Cell *high_word, Cell *low_word);
Cell mul(Cell x, Cell y);
void divide(Cell n1, Cell n0, Cell d, Cell *quotient, Cell *remainder);
Cell slash(Cell x, Cell y); /* the name 'div' is taken... */
void shift_left(Cell A, Cell X, unsigned long count, Cell *pA, Cell *pX);
void shift_right(Cell A, Cell X, unsigned long count, Cell *pA, Cell *pX);
void shift_left_circular(Cell A, Cell X, unsigned count, Cell *pA, Cell *pX);
void shift_left_binary(Cell A, Cell X, unsigned long count, Cell *pA, Cell *pX);
void shift_right_binary(Cell A, Cell X, unsigned long count, Cell *pA, Cell *pX);
Cell logical_sum(Cell x, Cell y);
Cell logical_difference(Cell x, Cell y);
Cell logical_product(Cell x, Cell y);
Cell float_add(Cell x, Cell y);
Cell float_subtract(Cell x, Cell y);
Cell float_multiply(Cell x, Cell y);
Cell float_divide(Cell x, Cell y);
Cell float_flot(Cell x);
Cell float_fix(Cell x);
int float_compare(Cell x, Cell y);
/* Break a cell into its component fields. */
#define destructure_cell(cell, A, I, F, C) \
do { \
Cell temp_ = (cell); \
Cell sign_ = sign_bit(temp_); \
C = temp_ & 63; \
F = (temp_ >>= 6) & 63; \
I = (temp_ >>= 6) & 63; \
A = sign_ | (4095 & (temp_ >> 6)); \
} while (0)
/* --- Printable representation --- */
const char *index_to_string(Cell index);
void print_cell(Cell cell);
void unparse_cell(char *buffer, Cell cell, Flag disasm);
/* Pre: 16 <= sizeof(buffer) */
/* --- Addresses --- */
typedef int Address;
const char *address_to_string(Address address);
Cell address_to_cell(Address addr);
Address cell_to_address(Cell cell);
#endif