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22 lines
698 B
Groff
22 lines
698 B
Groff
.TH sub_of 3
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.SH NAME
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sub_of \- subtract two integers, check for arithmetic overflow
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.SH SYNTAX
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.B #include <libowfat/rangecheck.h>
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int \fBsub_of\fP(dest,a,b);
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.SH DESCRIPTION
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If calculating a-b is possible without causing undefined behavior or an
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arithmetic overflow in C, and the result fits into the destination
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integer type, do dest=a-b and return 0.
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Otherwise, return 1.
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Note: This is a macro, so dest does not have to be a pointer.
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.SH BUGS
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In the multiplication functions, a return value of 1 signals success and
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0 failure. In add_of, sub_of and assign it's the other way around.
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.SH "SEE ALSO"
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add_of(3), assign(3), imult16(3), umult16(3), imult32(3), umult32(3),
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imult64(3), umult64(3)
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