mirror of
https://github.com/afska/gba-link-connection.git
synced 2026-03-21 17:44:21 -05:00
118 lines
3.5 KiB
C++
118 lines
3.5 KiB
C++
#ifndef LINK_GPIO_H
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#define LINK_GPIO_H
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// --------------------------------------------------------------------------
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// A General Purpose Input-Output handler for the Link Port.
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// --------------------------------------------------------------------------
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// Usage:
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// - 1) Include this header in your main.cpp file and add:
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// LinkGPIO* linkGPIO = new LinkGPIO();
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// - 2) Initialize the library with:
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// linkGPIO->reset();
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// - 3) Write pins by using:
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// linkGPIO->setMode(LinkGPIO::Pin::SD, LinkGPIO::Direction::OUTPUT);
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// linkGPIO->writePin(LinkGPIO::Pin::SD, true);
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// - 4) Read pins by using:
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// linkGPIO->setMode(LinkGPIO::Pin::SC, LinkGPIO::Direction::INPUT);
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// bool isHigh = linkGPIO->readPin(LinkGPIO::Pin::SC);
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// - 5) Subscribe to SI falling:
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// linkGPIO->setSIInterrupts(true);
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// // (when SI changes from high to low, an IRQ will be generated)
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// --------------------------------------------------------------------------
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// considerations:
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// - always set the SI terminal to an input!
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// - call reset() when you finish doing GPIO stuff!
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// --------------------------------------------------------------------------
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#ifndef LINK_DEVELOPMENT
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#pragma GCC system_header
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#endif
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#include "_link_common.hpp"
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/**
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* @brief A General Purpose Input-Output handler for the Link Port.
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*/
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class LinkGPIO {
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private:
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using u32 = unsigned int;
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using u16 = unsigned short;
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using u8 = unsigned char;
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static constexpr int RCNT_GENERAL_PURPOSE = (1 << 15);
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static constexpr int SIOCNT_GENERAL_PURPOSE = 0;
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static constexpr int BIT_SI_INTERRUPT = 8;
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static constexpr u8 DATA_BITS[] = {2, 3, 1, 0};
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static constexpr u8 DIRECTION_BITS[] = {6, 7, 5, 4};
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public:
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enum Pin { SI, SO, SD, SC };
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enum Direction { INPUT, OUTPUT };
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/**
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* @brief Resets communication mode to General Purpose.
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* \warning Required to initialize the library!
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*/
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void reset() {
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Link::_REG_RCNT = RCNT_GENERAL_PURPOSE;
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Link::_REG_SIOCNT = SIOCNT_GENERAL_PURPOSE;
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}
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/**
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* @brief Configures a `pin` to use a `direction` (input or output).
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* @param pin One of the enum values from `LinkGPIO::Pin`.
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* @param direction One of the enum values from `LinkGPIO::Direction`.
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*/
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void setMode(Pin pin, Direction direction) {
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setBit(Link::_REG_RCNT, DIRECTION_BITS[pin],
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direction == Direction::OUTPUT);
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}
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/**
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* @brief Returns the direction set at `pin`.
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*/
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[[nodiscard]] Direction getMode(Pin pin) {
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return Direction(getBit(Link::_REG_RCNT, DIRECTION_BITS[pin]));
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}
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/**
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* @brief Returns whether a `pin` is *HIGH* or not (when set as an input).
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* @param pin One of the enum values from `LinkGPIO::Pin`.
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*/
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[[nodiscard]] bool readPin(Pin pin) {
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return (Link::_REG_RCNT & (1 << DATA_BITS[pin])) != 0;
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}
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/**
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* @brief Sets a `pin` to be high or not (when set as an output).
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* @param pin One of the enum values from `LinkGPIO::Pin`.
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* @param isHigh `true` = HIGH, `false` = LOW.
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*/
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void writePin(Pin pin, bool isHigh) {
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setBit(Link::_REG_RCNT, DATA_BITS[pin], isHigh);
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}
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/**
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* @brief If it `isEnabled`, an IRQ will be generated when `SI` changes from
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* HIGH to LOW.
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* @param isEnabled Enable SI-falling interrupts.
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*/
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void setSIInterrupts(bool isEnabled) {
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setBit(Link::_REG_RCNT, BIT_SI_INTERRUPT, isEnabled);
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}
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private:
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int getBit(u16 reg, int bit) { return (reg >> bit) & 1; }
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void setBit(volatile u16& reg, int bit, bool data) {
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if (data)
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reg |= 1 << bit;
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else
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reg &= ~(1 << bit);
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}
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};
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extern LinkGPIO* linkGPIO;
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#endif // LINK_GPIO_H
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