mixing C and assembly
in [Embedded]
|
Prev: Loop back fails
Next: china wholesale cheap nike air max 87 90 95 ltd tn shoes bapesta hogan sneakers china suppliers www.voguesonline.net
From: Grant Edwards on 22 Apr 2008 11:53 On 2008-04-22, Lax <Lax.Clarke(a)gmail.com> wrote: > Are there any situations where programming an embedded > processor "requires" at least some assembly code? Usually. > How about for AVR, MSP430, 68HC11, 8051(Atmel)? Yes. > Can these 4 microcontrollers be programmed fully in C without > touching assembly (even interrupts and etc.)? Sometimes. It depends on the toolchain and on the job to be done. Most toolchains provide C extensions to do things like interrupts and access special hardware features. If those extensions are sufficient for what you need to do, then you don't need to write assembly code. If they aren't, then you do. -- Grant Edwards grante Yow! ... or were you at driving the PONTIAC that visi.com HONKED at me in MIAMI last Tuesday?
From: Bill Leary on 22 Apr 2008 12:51 "Lax" <Lax.Clarke(a)gmail.com> wrote in message news:2defcf6d-7dab-4699-9ce1-d433240398e4(a)m36g2000hse.googlegroups.com... > Are there any situations where programming an embedded processor > "requires" at least some assembly code? In every case where I've worked an embedded processor directly, I've had to at least initialize the environment so it could run C. Basically, setup the stack, clear RAM and jump to _main. In cases where there's an OS on it already, and that has an applications hook, then it could have been done with only C. In some cases, however, it's been expedient to use some assembler. > How about for AVR, MSP430, 68HC11, 8051(Atmel)? > Can these 4 microcontrollers be programmed fully in C without touching > assembly (even interrupts and etc.)? I have no experience with the first two. For the last two, without an OS, yes. With an OS, for the 68HC11 I did for expediency, but could have avoided it, but for the 8051 I had to do some assembly. Perhaps selection of a different OS or development package would have made it possible to avoid assembler. - Bill
From: linnix on 22 Apr 2008 13:31 On Apr 22, 9:51 am, "Bill Leary" <Bill_Le...(a)msn.com> wrote: > "Lax" <Lax.Cla...(a)gmail.com> wrote in message > > news:2defcf6d-7dab-4699-9ce1-d433240398e4(a)m36g2000hse.googlegroups.com... > > > Are there any situations where programming an embedded processor > > "requires" at least some assembly code? > > In every case where I've worked an embedded processor directly, I've had to > at least initialize the environment so it could run C. Basically, setup the > stack, clear RAM and jump to _main. There are always assembly involved somewhere, but you don't have to write them. Why are you re-inventing run-time libraries? > > In cases where there's an OS on it already, and that has an applications > hook, then it could have been done with only C. In some cases, however, > it's been expedient to use some assembler. > > > How about for AVR, MSP430, 68HC11, 8051(Atmel)? > > Can these 4 microcontrollers be programmed fully in C without touching > > assembly (even interrupts and etc.)? Yes for AVR, you can interrupt, sleep, powerdown and change clock speeds in C. The only assembly I have used is to load flash codes into data space, for which there is no C equivalent. > > I have no experience with the first two. For the last two, without an OS, > yes. With an OS, for the 68HC11 I did for expediency, but could have > avoided it, but for the 8051 I had to do some assembly. Perhaps selection > of a different OS or development package would have made it possible to > avoid assembler. > > - Bill
From: Walter Banks on 22 Apr 2008 13:39 Vladimir Vassilevsky wrote: > You have to resort to assembly in the two special cases: > > 1. The system level work like switching the contexts of the tasks, C > startup code, etc. > > 2. The parts of code where the performance is very critical. > > Other then that, everything can be done in C. Vladimir, In your second point I would qualify it to parts of code requiring exact timing on anything that we have released recently that seems to be the only limitation. Regards, -- Walter Banks Byte Craft Limited Tel. (519) 888-6911 http://www.bytecraft.com walter(a)bytecraft.com
From: Grant Edwards on 22 Apr 2008 14:25
On 2008-04-22, Bill Leary <Bill_Leary(a)msn.com> wrote: > "Lax" <Lax.Clarke(a)gmail.com> wrote in message > news:2defcf6d-7dab-4699-9ce1-d433240398e4(a)m36g2000hse.googlegroups.com... >> Are there any situations where programming an embedded processor >> "requires" at least some assembly code? > > In every case where I've worked an embedded processor directly, I've had to > at least initialize the environment so it could run C. Basically, setup the > stack, clear RAM and jump to _main. For processors without an external bus (IOW they have a fixed memory map), many toolchains will provide startup code that does all that. That's certainly true for GCC on the Atmel AVR and TI MSP430: tell the compiler which part you're using, and you don't have to write a lick of startup code. -- Grant Edwards grante Yow! Did something bad at happen or am I in a visi.com drive-in movie?? |