1 USING: generic help.markup help.syntax kernel math
2 memory namespaces sequences kernel.private classes
3 classes.builtin sequences.private ;
7 { $var-description "Number of least significant bits reserved for a type tag in a tagged pointer." }
11 { $var-description "Taking the bitwise and of a tagged pointer with this mask leaves the tag." } ;
14 { $var-description "Number of distinct built-in types. This is one more than the maximum value from the " { $link tag } " primitive." } ;
17 { $values { "class" class } { "n" "an integer or " { $link f } } }
18 { $description "Outputs the built-in type number instances of " { $link class } ". Will output " { $link f } " if this is not a built-in class." }
19 { $see-also builtin-class } ;
22 { $values { "n" integer } { "tagged" integer } }
23 { $description "Outputs a tagged fixnum." } ;
26 { $values { "n" "number of bits in a fixnum" } } ;
29 { $values { "n" "smallest positive integer not representable by a fixnum" } } ;
31 HELP: most-positive-fixnum
32 { $values { "n" "largest positive integer representable by a fixnum" } } ;
34 HELP: most-negative-fixnum
35 { $values { "n" "smallest negative integer representable by a fixnum" } } ;
37 HELP: bootstrap-first-bignum
38 { $values { "n" "smallest positive integer not representable by a fixnum" } }
39 { $description "Outputs the value for the target architecture when bootstrapping." } ;
41 HELP: bootstrap-most-positive-fixnum
42 { $values { "n" "largest positive integer representable by a fixnum" } }
43 { $description "Outputs the value for the target architecture when bootstrapping." } ;
45 HELP: bootstrap-most-negative-fixnum
46 { $values { "n" "smallest negative integer representable by a fixnum" } }
47 { $description "Outputs the value for the target architecture when bootstrapping." } ;
50 { $values { "n" "a positive integer" } }
51 { $description "Outputs the pointer size in bytes of the current CPU architecture." } ;
54 { $values { "m" integer } { "n" integer } }
55 { $description "Computes the number of bytes used by " { $snippet "m" } " CPU operand-sized cells." } ;
58 { $values { "n" integer } }
59 { $description "Outputs the number of bits in one CPU operand-sized cell." } ;
62 { $values { "n" "a positive integer" } }
63 { $description "Outputs the pointer size in bytes for the target image (if bootstrapping) or the current CPU architecture (otherwise)." } ;
66 { $values { "m" integer } { "n" integer } }
67 { $description "Computes the number of bytes used by " { $snippet "m" } " cells in the target image (if bootstrapping) or the current CPU architecture (otherwise)." } ;
69 HELP: bootstrap-cell-bits
70 { $values { "n" integer } }
71 { $description "Outputs the number of bits in one cell in the target image (if bootstrapping) or the current CPU architecture (otherwise)." } ;
74 { $class-description "Union class of all values that the Factor VM can store immediately, all others are stored as references (pointer) to them." } ;
76 ARTICLE: "layouts-types" "Type numbers"
77 "Corresponding to every built-in class is a built-in type number. An object can be asked for its built-in type number:"
79 "Built-in type numbers can be converted to classes, and vice versa:"
85 { $see-also "builtin-classes" } ;
87 ARTICLE: "layouts-tags" "Tagged pointers"
88 "Every pointer stored on the stack or in the heap has a " { $emphasis "tag" } ", which is a small integer identifying the type of the pointer. If the tag is not equal to one of the two special tags, the remaining bits contain the memory address of a heap-allocated object. The two special tags are the " { $link fixnum } " tag and the " { $link f } " tag."
90 "Words for working with tagged pointers:"
95 "The Factor VM does not actually expose any words for working with tagged pointers directly. The above words operate on integers; they are used in the bootstrap image generator and the optimizing compiler." ;
97 ARTICLE: "layouts-limits" "Sizes and limits"
98 "Processor cell size:"
104 "Range of integers representable by " { $link fixnum } "s:"
109 "Maximum array size:"
110 { $subsections max-array-capacity } ;
112 ARTICLE: "layouts-bootstrap" "Bootstrap support"
113 "Processor cell size for the target architecture:"
119 "Range of integers representable by " { $link fixnum } "s of the target architecture:"
121 bootstrap-most-negative-fixnum
122 bootstrap-most-positive-fixnum
124 "Maximum array size for the target architecture:"
125 { $subsections bootstrap-max-array-capacity } ;
127 ARTICLE: "layouts" "VM memory layouts"
128 "The words documented in this section do not ever need to be called by user code. They are documented for the benefit of those wishing to explore the internals of Factor's implementation."