re-entrant function in Keil-4 RVMDK
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From: kishor on 31 May 2010 04:29 Hi friends, I am new to keil-4 RVMDK & luminary micro lm3s6965. I want to use some functions as re-entrant. In keil C51, they provide keyword "reentrant", But in RVMDK I didn't find any clue. Thanks & Regards, Kishore
From: Chris H on 31 May 2010 06:43 In message <28b1633b-6012-44cc-ba7c-0396877f57cf(a)g39g2000pri.googlegroup s.com>, kishor <kiishor(a)gmail.com> writes >Hi friends, > >I am new to keil-4 RVMDK & luminary micro lm3s6965. >I want to use some functions as re-entrant. > >In keil C51, they provide keyword "reentrant", But in RVMDK I didn't >find any clue. Have you asked Keil tech support? -- \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ \/\/\/\/\ Chris Hills Staffs England /\/\/\/\/ \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/
From: David Brown on 31 May 2010 10:00 On 31/05/2010 10:29, kishor wrote: > Hi friends, > > I am new to keil-4 RVMDK& luminary micro lm3s6965. > I want to use some functions as re-entrant. > > In keil C51, they provide keyword "reentrant", But in RVMDK I didn't > find any clue. > > Thanks& Regards, > Kishore You make a function re-entrant by writing appropriate C code - avoid using shared storage (such as global variables or function-scope statics), avoid calling non-re-entrant functions, etc. It's only on non-standard compilers for seriously limited processors - such as Keil's C51 compiler - that you will see a "reentrant" keyword. For processors that can efficiently access data on a stack, or with compilers that are smart enough to figure out these things automatically and thus generate good code while following C standards (I don't know if such a compiler exists for the 8051), there is no such thing as a "reentrant" keyword.
From: Chris H on 31 May 2010 11:21 In message <4c03c115$0$4149$8404b019(a)news.wineasy.se>, David Brown <david(a)westcontrol.removethisbit.com> writes >On 31/05/2010 10:29, kishor wrote: >> Hi friends, >> >> I am new to keil-4 RVMDK& luminary micro lm3s6965. >> I want to use some functions as re-entrant. >> >> In keil C51, they provide keyword "reentrant", But in RVMDK I didn't >> find any clue. >> >> Thanks& Regards, >> Kishore > > >You make a function re-entrant by writing appropriate C code - avoid >using shared storage (such as global variables or function-scope >statics), avoid calling non-re-entrant functions, etc. > >It's only on non-standard compilers for seriously limited processors - >such as Keil's C51 compiler - that you will see a "reentrant" keyword. Keil is no more "non-standard" than most other compilers.... GCC for example. >For processors that can efficiently access data on a stack, or with >compilers that are smart enough to figure out these things >automatically and thus generate good code while following C standards >(I don't know if such a compiler exists for the 8051), there is no such >thing as a "reentrant" keyword. The only sensible compiler for the 8051 is the Keil which has about 80% of the market. -- \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ \/\/\/\/\ Chris Hills Staffs England /\/\/\/\/ \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/
From: David Brown on 31 May 2010 15:33
Chris H wrote: > In message <4c03c115$0$4149$8404b019(a)news.wineasy.se>, David Brown > <david(a)westcontrol.removethisbit.com> writes >> On 31/05/2010 10:29, kishor wrote: >>> Hi friends, >>> >>> I am new to keil-4 RVMDK& luminary micro lm3s6965. >>> I want to use some functions as re-entrant. >>> >>> In keil C51, they provide keyword "reentrant", But in RVMDK I didn't >>> find any clue. >>> >>> Thanks& Regards, >>> Kishore >> >> You make a function re-entrant by writing appropriate C code - avoid >> using shared storage (such as global variables or function-scope >> statics), avoid calling non-re-entrant functions, etc. >> >> It's only on non-standard compilers for seriously limited processors - >> such as Keil's C51 compiler - that you will see a "reentrant" keyword. > > Keil is no more "non-standard" than most other compilers.... GCC for > example. > I was wondering if you could resist... Of course, all embedded compilers have non-standard features - there are things that an embedded C programmer wants to be able to express that cannot be expressed in C (such as interrupt functions, embedded assembly, data in flash or other specific memory areas, etc.). Additionally, many compilers (embedded or otherwise) have extensions or extra features to help you write smaller, faster, or otherwise better code. They also often allow you to mix features from different standards, such as allowing // comments or inline functions in ANSI C. gcc has plenty of such extensions if you want to use them, as do many (all?) other compilers. But as these are optional, they are not non-standard. Where Keil's 8051 compiler differs here is that it requires non-standard extension keywords to write code that can be expressed correctly in standard C. Re-entrant functions are not a special embedded feature, but part of the language. If you cannot write a re-entrant (or recursive) function in plain standard C, then the compiler is non-standard in a much more serious way than most other embedded compilers. Of course, it could be that there are command-line switches for Keil that allow any functions to be re-entrant, thus making the compiler more standards compliant (but perhaps generating horrible code). I have never had to use the 8051, so I don't know the tools in detail. But the little I've seen of code written for either Keil or SDCC for the 8051 has had a mishmash of extra keywords saying whether data is to be placed in registers, internal ram, xdata, or whatever. That's not standard C. That does not mean there is anything wrong with it, of course - the compiler is a tool to let you write code to run on the target. If it has to be non-standard to let you generate good object code, then that's fair enough. >> For processors that can efficiently access data on a stack, or with >> compilers that are smart enough to figure out these things >> automatically and thus generate good code while following C standards >> (I don't know if such a compiler exists for the 8051), there is no such >> thing as a "reentrant" keyword. > > The only sensible compiler for the 8051 is the Keil which has about 80% > of the market. > |