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updated for photo-typesetter

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dick
1986-02-04 17:37:41 +00:00
parent f3e2248cc4
commit 9694054674
19 changed files with 3724 additions and 2420 deletions
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17
doc/em/types.nr
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@@ -33,7 +33,7 @@ restrictions imposed on the representation of the types used.
A number \fBn\fP used in these paragraphs indicates the size of
the object in \fIbits\fP.
.S2 "Unsigned integers"
The range of unsigned integers is 0..2\v'-0.5m'\fBn\fP\v'0.5m'-1.
The range of unsigned integers is 0..2\v'-0.5m'\fBn\fP\v'0.5m'\-1.
A binary representation is assumed.
The order of the bits within an object is knowingly left
unspecified.
@@ -60,21 +60,22 @@ and expect a correct result.
We assume existence of at least single word unsigned arithmetic
in any implementation.
.S2 "Signed Integers"
The range of signed integers is -2\v'-0.5m'\fBn\fP-1\v'0.5m'~..~2\v'-0.5m'\fBn\fP-1\v'0.5m'-1,
The range of signed integers is
\-2\v'-0.5m'\fBn\fP\-1\v'0.5m'~..~2\v'-0.5m'\fBn\fP\-1\v'0.5m'\-1,
in other words the range of signed integers of \fBn\fP bits
using two's complement arithmetic.
The representation is the same as for unsigned integers except
the range 2\v'-0.5m'\fBn\fP-1\v'0.5m'~..~2\v'-0.5m'\fBn\fP\v'0.5m'-1 is mapped on the
range -2\v'-0.5m'\fBn\fP-1\v'0.5m'~..~-1.
The representation is the same as for unsigned integers except the range
2\v'-0.5m'\fBn\fP\-1\v'0.5m'~..~2\v'-0.5m'\fBn\fP\v'0.5m'\-1 is mapped on the
range \-2\v'-0.5m'\fBn\fP\-1\v'0.5m'~..~\-1.
In other words, the most significant bit is used as sign bit.
The convert instructions between signed and unsigned integers
of the same size can be used to catch errors.
.A
The value -2\v'-0.5m'\fBn\fP-1\v'0.5m' is used for undefined
The value \-2\v'-0.5m'\fBn\fP\-1\v'0.5m' is used for undefined
signed integers.
EM implementations should trap when this value is used in an
operation on signed integers.
The instruction mask, accessed with SIM and LIM -~see chapter 9~- ,
The instruction mask, accessed with SIM and LIM \-~see chapter 9~\- ,
can be used to disable such traps.
.A
We assume existence of at least single word signed arithmetic
@@ -126,5 +127,5 @@ the value of the unsigned integer is the summation of the
Example: a 2-word bit set (wordsize 2) containing the
elements 1, 6, 8, 15, 18, 21, 27 and 28 is composed of two
integers, e.g. at addresses 40 and 42.
The word at 40 contains the value 33090 (or~-32446),
The word at 40 contains the value 33090 (or~\-32446),
the word at 42 contains the value 6180.