On Tuesday, September 12, 2017 at 5:37:31 PM UTC+2, Johannes Bauer wrote: > Hi group, > > so I'm having a problem that I'd like to solve *nicely*. I know plenty > of ways to solve it, but am curious if there's a solution that allows me > to write the solution in a way that is most comfortable for the user. > > I'm trying to map registers of a processor. So assume you have a n bit > address space, the processor might have duplicate units of identical > functionality mapped at different places in memory. For example, assume > there's a GPIO unit that has registers FOO, BAR and KOO and two GPIO > ports GPIOA and GPIOB. I'd like to write code along the lines of this: > > class GpioMap(BaseRegisterMap): > FOO = 0x0 > BAR = 0x4 > KOO = 0x8 > > class CPURegisterMap(BaseRegisterMap): > GPIOA = GpioMap(0x10000) > GPIOB = GpioMap(0x20000) > > cpu = CPURegisterMap(0x80000000) > > assert(cpu.addr == 0x80000000) > assert(cpu.GPIOA.addr == 0x80000000 + 0x10000) > assert(cpu.GPIOB.addr == 0x80000000 + 0x20000) > assert(cpu.GPIOA.FOO.addr == 0x80000000 + 0x10000 + 0x0) > assert(cpu.GPIOA.KOO.addr == 0x80000000 + 0x10000 + 0x8) > assert(cpu.GPIOB.BAR.addr == 0x80000000 + 0x20000 + 0x4) > > So, obviously, FOO, BAR and KOO are of type "int" without any "addr" > property, so there would need to be some magic there. Additionally, > through some way the instanciation of GpioMap() would need the knowledge > of its parent base, which I'm not sure is even possible. Maybe (that's > what I'm currently trying to get right) the __getattribute__ would > propagate the information about the accumulated parent's base address to > the child during lookup. > > Anyways, I'm looking for your ideas on how to solve such a thing > "nicely". Note that "BaseRegisterMap" is allowed to do dirty things as > long as the definition code has a clean look & feel. > > Cheers, > Joe > > > -- > >> Wo hattest Du das Beben nochmal GENAU vorhergesagt? > > Zumindest nicht öffentlich! > Ah, der neueste und bis heute genialste Streich unsere großen > Kosmologen: Die Geheim-Vorhersage. > - Karl Kaos über Rüdiger Thomas in dsa <hidbv3$om2$1...@speranza.aioe.org>
A child (e.g. instance of GpioMap) should not have any knowledge of it's own base address. This is a function of the GPIORegisyerMap only. i.e. The GPIORegisyerMap would do the selection of particular instance. It may be worth looking at some of the IP-XACT documentation, which defines some common terms (IIRC register, address map, address space etc). Having a consistent definition here will definitely help moving forward Although it may seem OTT at the moment, it is something you should consider at the outset. e.g. A single GPIO register may occur at two different addresses, depending on the bus master (CPU Core, Debugger, External SPI access). Steven -- https://mail.python.org/mailman/listinfo/python-list
