stm32xx-sys: configure GPIO IRQ edge with an enum #1706
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The current `Sys::gpio_irq_configure` IPC interface is a bit confusing, as it takes two `bool`s for the rising and falling edge sensitivities, as in: ```rust sys.gpio_irq_configure(mask, true, false); ``` This isn't particularly clear for a reader, who then has to remember the order of the arguments to determine which edge sensitivity is being enabled here. This is a case of ["boolean blindness"][1]. This commit improves the interface by changing it to take an `enum` with variants for `Rising`, `Falling`, and `Both`. Now, the same call to the IPC looks like this: ```rust sys.gpio_irq_configure(mask, Edge::Rising); ``` which should be much more obvious to a reader, who no longer needs to remember the argument ordering to decypher calls to this function. Also, this has the advantage of preventing the case where both rising and falling edge sensitivities are disabled at compile-time. Currently, this is a runtime error (reply fault), but with the new interface, a caller can provide an invalid configuration if they hand-write the input buffer rather than using the Idol client stub, so it should be harder to mess up. [1]: https://runtimeverification.com/blog/code-smell-boolean-blindness
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cbiffle
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Apr 2, 2024
Signed-off-by: Eliza Weisman <eliza@elizas.website>
bcantrill
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Apr 2, 2024
Signed-off-by: Eliza Weisman <eliza@elizas.website>
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The current `Sys::gpio_irq_configure` IPC interface is a bit confusing, as it takes two `bool`s for the rising and falling edge sensitivities, as in: ```rust sys.gpio_irq_configure(mask, true, false); ``` This isn't particularly clear for a reader, who then has to remember the order of the arguments to determine which edge sensitivity is being enabled here. This is a case of ["boolean blindness"][1]. This commit improves the interface by changing it to take an `enum` with variants for `Rising`, `Falling`, and `Both`. Now, the same call to the IPC looks like this: ```rust sys.gpio_irq_configure(mask, Edge::Rising); ``` which should be much more obvious to a reader, who no longer needs to remember the argument ordering to decypher calls to this function. Also, this has the advantage of preventing the case where both rising and falling edge sensitivities are disabled at compile-time. Currently, this is a runtime error (reply fault), but with the new interface, a caller can provide an invalid configuration if they hand-write the input buffer rather than using the Idol client stub, so it should be harder to mess up. [1]: https://runtimeverification.com/blog/code-smell-boolean-blindness
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The current
Sys::gpio_irq_configureIPC interface is a bit confusing, as it takes twobools for the rising and falling edge sensitivities, as in:This isn't particularly clear for a reader, who then has to remember the order of the arguments to determine which edge sensitivity is being enabled here. This is a case of "boolean blindness".
This commit improves the interface by changing it to take an
enumwith variants forRising,Falling, andBoth. Now, the same call to the IPC looks like this:which should be much more obvious to a reader, who no longer needs to remember the argument ordering to decypher calls to this function.
Also, this has the advantage of preventing the case where both rising and falling edge sensitivities are disabled at compile-time. Currently, this is a runtime error (reply fault), but with the new interface, a caller can provide an invalid configuration if they hand-write the input buffer rather than using the Idol client stub, so it should be harder to mess up.