| blob | 9bc04ab83579c1daf91e17ae75dedbe50b9d5003 |
1 .TH INT64 3
2 .SH NAME
3 int64, add64, add64u, add64ul, sub64, sub64u, sub64ul, diff64, cvu64, cvul64, cv64u, cv64ul, div64u, rem64u, mul64u, cmp64, cmp64u, cmp64ul, ex64lo, ex64hi, make64 \- 64 bit disk offset computations
4 .SH SYNOPSIS
5 .ft B
6 .nf
7 #include <minix/u64.h>
9 u64_t add64(u64_t \fIi\fP, u64_t \fIj\fP)
10 u64_t add64u(u64_t \fIi\fP, unsigned \fIj\fP)
11 u64_t add64ul(u64_t \fIi\fP, unsigned long \fIj\fP)
12 u64_t sub64(u64_t \fIi\fP, u64_t \fIj\fP)
13 u64_t sub64u(u64_t \fIi\fP, unsigned \fIj\fP)
14 u64_t sub64ul(u64_t \fIi\fP, unsigned long \fIj\fP)
15 unsigned diff64(u64_t \fIi\fP, u64_t \fIj\fP)
16 u64_t cvu64(unsigned \fIi\fP)
17 u64_t cvul64(unsigned long \fIi\fP)
18 unsigned cv64u(u64_t \fIi\fP)
19 unsigned long cv64ul(u64_t \fIi\fP)
20 unsigned long div64u(u64_t \fIi\fP, unsigned \fIj\fP)
21 unsigned rem64u(u64_t \fIi\fP, unsigned \fIj\fP)
22 u64_t mul64u(unsigned long \fIi\fP, unsigned \fIj\fP)
23 int cmp64(u64_t \fIi\fP, u64_t \fIj\fP)
24 int cmp64u(u64_t \fIi\fP, unsigned \fIj\fP)
25 int cmp64ul(u64_t \fIi\fP, unsigned long \fIj\fP)
26 unsigned long ex64lo(u64_t \fIi\fP)
27 unsigned long ex64hi(u64_t \fIi\fP)
28 u64_t make64(unsigned long \fIlo\fP, unsigned long \fIhi\fP)
29 .fi
30 .ft P
31 .SH DESCRIPTION
32 .de SP
33 .if t .sp 0.4
34 .if n .sp
35 ..
36 The
37 .B int64
38 family of functions allow MINIX 3 to handle disks of up to 4 terabytes using
39 32 bit sector numbers and 64 bit byte offsets on a machine where the C type
40 .B long
41 is 32 bits. The <minix/u64.h> include file defines a 64 bit data
42 type,
43 .BR u64_t ,
44 and a number of functions to operate on them. Note that these functions are
45 geared towards common disk offset and block computations, and do not provide
46 a full set of 64 bit operations. They are:
47 .PP
48 .TP
49 .B "u64_t add64(u64_t \fIi\fP, u64_t \fIj\fP)"
50 Add the 64 bit numbers
51 .I i
52 and
53 .I j
54 forming a 64 bit result.
55 .TP
56 .B "u64_t add64u(u64_t \fIi\fP, unsigned \fIj\fP)"
57 Add an unsigned
58 .I j
59 to a 64 bit number
60 .I i
61 forming a 64 bit result.
62 .TP
63 .B "u64_t add64ul(u64_t \fIi\fP, unsigned long \fIj\fP)"
64 Add an unsigned long
65 .I j
66 to a 64 bit number
67 .I i
68 forming a 64 bit result.
69 .TP
70 .B "u64_t sub64(u64_t \fIi\fP, u64_t \fIj\fP)"
71 Subtract the 64 bit number
72 .I j
73 from the 64 bit number
74 .I i
75 forming a 64 bit result.
76 .TP
77 .B "u64_t sub64u(u64_t \fIi\fP, unsigned \fIj\fP)"
78 Subtract the unsigned
79 .I j
80 from the 64 bit number
81 .I i
82 forming a 64 bit result.
83 .TP
84 .B "u64_t sub64ul(u64_t \fIi\fP, unsigned long \fIj\fP)"
85 Subtract the unsigned long
86 .I j
87 from the 64 bit number
88 .I i
89 forming a 64 bit result.
90 .TP
91 .B "unsigned diff64(u64_t \fIi\fP, u64_t \fIj\fP)"
92 Subtract the 64 bit number
93 .I j
94 from the 64 bit number
95 .I i
96 forming an unsigned. Overflow is not checked.
97 .TP
98 .B "u64_t cvu64(unsigned \fIi\fP)"
99 Convert an unsigned to a 64 bit number.
100 .TP
101 .B "u64_t cvul64(unsigned long \fIi\fP)"
102 Convert an unsigned long to a 64 bit number.
103 .TP
104 .B "unsigned cv64u(u64_t \fIi\fP)"
105 Convert a 64 bit number to an unsigned if it fits, otherwise return
106 .BR UINT_MAX .
107 .TP
108 .B "unsigned long cv64ul(u64_t \fIi\fP)"
109 Convert a 64 bit number to an unsigned long if it fits, otherwise return
110 .BR ULONG_MAX .
111 .TP
112 .B "unsigned long div64u(u64_t \fIi\fP, unsigned \fIj\fP)"
113 Divide the 64 bit number
114 .I i
115 by the unsigned
116 .I j
117 giving an unsigned long. Overflow is not checked. (Typical "byte offset to
118 block number" conversion.)
119 .TP
120 .B "unsigned rem64u(u64_t \fIi\fP, unsigned \fIj\fP)"
121 Compute the remainder of the division of the 64 bit number
122 .I i
123 by the unsigned
124 .I j
125 as an unsigned. (Typical "byte offset within a block" computation.)
126 .TP
127 .B "u64_t mul64u(unsigned long \fIi\fP, unsigned \fIj\fP)"
128 Multiply the unsigned long
129 .I i
130 by the unsigned
131 .I j
132 giving a 64 bit number. (Typical "block number to byte offset" conversion.)
133 .TP
134 .B "int cmp64(u64_t \fIi\fP, u64_t \fIj\fP)"
135 Compare two 64 bit numbers.
136 Returns
137 .B -1
138 if
139 .I i
140 <
141 .IR j ,
142 .B 0
143 if
144 .I i
145 ==
146 .IR j ,
147 and
148 .B 1
149 if
150 .I i
151 >
152 .IR j .
153 .TP
154 .B "int cmp64u(u64_t \fIi\fP, unsigned \fIj\fP)"
155 Likewise compare a 64 bit number with an unsigned.
156 .TP
157 .B "int cmp64ul(u64_t \fIi\fP, unsigned long \fIj\fP)"
158 Likewise compare a 64 bit number with an unsigned long.
159 .TP
160 .B "unsigned long ex64lo(u64_t \fIi\fP)"
161 Extract the low 32 bits of a 64 bit number.
162 .TP
163 .B "unsigned long ex64hi(u64_t \fIi\fP)"
164 Extract the high 32 bits of a 64 bit number.
165 .TP
166 .B "u64_t make64(unsigned long \fIlo\fP, unsigned long \fIhi\fP)"
167 Combine the low and high parts of a 64 bit number to a 64 bit number. (The
168 last three functions are used to pass 64 bit numbers in messages within the
169 kernel. They should not be used for anything else.)
170 .SH "SEE ALSO"
171 .BR fcntl (2),
172 .BR controller (4).
173 .SH NOTES
174 With the usual disk block size of 512 bytes the maximum disk size is 512
175 \(** 4 gigabytes = 2 terabytes.
176 .PP
177 Standard MINIX 3 only uses 64 bit computations within the disk drivers, so
178 individual partitions are still limited to 4 gigabytes. Minix-vmd has 64
179 bit computations also in the file system code.
180 .PP
181 Special care must be taken when accessing disk devices. For MINIX 3 one may
182 have to temporarily change the start of the partition to go beyond 4 G.
183 Minix-vmd can go beyond 4 G, but the
184 .B lseek
185 system call is still limited to a 32 bit offset. One needs to use
186 .PP
187 .RS
188 .BI "fcntl(" fd ", F_SEEK, u64_t " offset ")"
189 .RE
190 .PP
191 to seek to a 64 bit position.
192 .SH AUTHOR
193 Kees J. Bot <kjb@cs.vu.nl>