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author | Joel Sherrill <joel.sherrill@OARcorp.com> | 1997-05-27 12:40:11 +0000 |
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committer | Joel Sherrill <joel.sherrill@OARcorp.com> | 1997-05-27 12:40:11 +0000 |
commit | ae68ff085724dd35d60151bd153e80b8b0776873 (patch) | |
tree | 2f1535a0497f5b872a4744ae13c9264b77e89c11 /doc/supplements/i960/cpumodel.texi | |
parent | This commit was generated by cvs2svn to compensate for changes in r832, (diff) | |
download | rtems-ae68ff085724dd35d60151bd153e80b8b0776873.tar.bz2 |
Initial revision
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diff --git a/doc/supplements/i960/cpumodel.texi b/doc/supplements/i960/cpumodel.texi new file mode 100644 index 0000000000..18ec1d7311 --- /dev/null +++ b/doc/supplements/i960/cpumodel.texi @@ -0,0 +1,79 @@ +@c +@c COPYRIGHT (c) 1988-1997. +@c On-Line Applications Research Corporation (OAR). +@c All rights reserved. +@c + +@ifinfo +@node CPU Model Dependent Features, CPU Model Dependent Features Introduction, Preface, Top +@end ifinfo +@chapter CPU Model Dependent Features +@ifinfo +@menu +* CPU Model Dependent Features Introduction:: +* CPU Model Dependent Features CPU Model Name:: +* CPU Model Dependent Features Floating Point Unit:: +@end menu +@end ifinfo + +@ifinfo +@node CPU Model Dependent Features Introduction, CPU Model Dependent Features CPU Model Name, CPU Model Dependent Features, CPU Model Dependent Features +@end ifinfo +@section Introduction + +Microprocessors are generally classified into +families with a variety of CPU models or implementations within +that family. Within a processor family, there is a high level +of binary compatibility. This family may be based on either an +architectural specification or on maintaining compatibility with +a popular processor. Recent microprocessor families such as the +SPARC or PA-RISC are based on an architectural specification +which is independent or any particular CPU model or +implementation. Older families such as the M68xxx and the iX86 +evolved as the manufacturer strived to produce higher +performance processor models which maintained binary +compatibility with older models. + +RTEMS takes advantage of the similarity of the +various models within a CPU family. Although the models do vary +in significant ways, the high level of compatibility makes it +possible to share the bulk of the CPU dependent executive code +across the entire family. Each processor family supported by +RTEMS has a list of features which vary between CPU models +within a family. For example, the most common model dependent +feature regardless of CPU family is the presence or absence of a +floating point unit or coprocessor. When defining the list of +features present on a particular CPU model, one simply notes +that floating point hardware is or is not present and defines a +single constant appropriately. Conditional compilation is +utilized to include the appropriate source code for this CPU +model's feature set. It is important to note that this means +that RTEMS is thus compiled using the appropriate feature set +and compilation flags optimal for this CPU model used. The +alternative would be to generate a binary which would execute on +all family members using only the features which were always +present. + +This chapter presents the set of features which vary +across i960 implementations and are of importance to RTEMS. +The set of CPU model feature macros are defined in the file +c/src/exec/score/cpu/i960/i960.h based upon the particular CPU +model defined on the compilation command line. + +@ifinfo +@node CPU Model Dependent Features CPU Model Name, CPU Model Dependent Features Floating Point Unit, CPU Model Dependent Features Introduction, CPU Model Dependent Features +@end ifinfo +@section CPU Model Name + +The macro CPU_MODEL_NAME is a string which designates +the name of this CPU model. For example, for the Intel i960CA, +this macro is set to the string "i960ca". + +@ifinfo +@node CPU Model Dependent Features Floating Point Unit, Calling Conventions, CPU Model Dependent Features CPU Model Name, CPU Model Dependent Features +@end ifinfo +@section Floating Point Unit + +The macro I960_HAS_FPU is set to 1 to indicate that +this CPU model has a hardware floating point unit and 0 +otherwise. |