projects / OpenSPARC-T2-SAM / blame
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| 55 | <H2><A NAME="SECTION007660000000000000000"></A><A NAME="decimal-threads"></A> | |
| 56 | <BR> | |
| 57 | 5.6.6 Working with threads | |
| 58 | </H2> | |
| 59 | ||
| 60 | <P> | |
| 61 | The <tt class="function">getcontext()</tt> function accesses a different <tt class="class">Context</tt> | |
| 62 | object for each thread. Having separate thread contexts means that threads | |
| 63 | may make changes (such as <code>getcontext.prec=10</code>) without interfering with | |
| 64 | other threads. | |
| 65 | ||
| 66 | <P> | |
| 67 | Likewise, the <tt class="function">setcontext()</tt> function automatically assigns its target | |
| 68 | to the current thread. | |
| 69 | ||
| 70 | <P> | |
| 71 | If <tt class="function">setcontext()</tt> has not been called before <tt class="function">getcontext()</tt>, | |
| 72 | then <tt class="function">getcontext()</tt> will automatically create a new context for use | |
| 73 | in the current thread. | |
| 74 | ||
| 75 | <P> | |
| 76 | The new context is copied from a prototype context called | |
| 77 | <var>DefaultContext</var>. To control the defaults so that each thread will use the | |
| 78 | same values throughout the application, directly modify the | |
| 79 | <var>DefaultContext</var> object. This should be done <em>before</em> any threads are | |
| 80 | started so that there won't be a race condition between threads calling | |
| 81 | <tt class="function">getcontext()</tt>. For example: | |
| 82 | ||
| 83 | <P> | |
| 84 | <div class="verbatim"><pre> | |
| 85 | # Set applicationwide defaults for all threads about to be launched | |
| 86 | DefaultContext.prec = 12 | |
| 87 | DefaultContext.rounding = ROUND_DOWN | |
| 88 | DefaultContext.traps = ExtendedContext.traps.copy() | |
| 89 | DefaultContext.traps[InvalidOperation] = 1 | |
| 90 | setcontext(DefaultContext) | |
| 91 | ||
| 92 | # Afterwards, the threads can be started | |
| 93 | t1.start() | |
| 94 | t2.start() | |
| 95 | t3.start() | |
| 96 | . . . | |
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