From ef16376aba1e224db5cad706257d93ba9d12ced2 Mon Sep 17 00:00:00 2001
From: Fabian Montero <fabian@posixlycorrect.com>
Date: Mon, 11 Sep 2023 02:05:35 -0600
Subject: [PATCH] add pin control library

---
 pin_control/main.c        |  13 +++++
 pin_control/pin_control.c | 102 ++++++++++++++++++++++++++++++++++++++
 pin_control/pin_control.h |  22 ++++++++
 pin_control/readme.md     |   1 +
 4 files changed, 138 insertions(+)
 create mode 100644 pin_control/main.c
 create mode 100644 pin_control/pin_control.c
 create mode 100644 pin_control/pin_control.h
 create mode 100644 pin_control/readme.md

diff --git a/pin_control/main.c b/pin_control/main.c
new file mode 100644
index 0000000..2b70c82
--- /dev/null
+++ b/pin_control/main.c
@@ -0,0 +1,13 @@
+#include "pin_control.h"
+
+int main() {
+    int button_pin = 5;
+    int button_response;
+
+
+    button_response = wait_for_button_press(button_pin);
+    printf("Button press detected on pin: %d\n", button_response);
+
+    cleanup_gpio();
+    return 0;
+}
diff --git a/pin_control/pin_control.c b/pin_control/pin_control.c
new file mode 100644
index 0000000..acf604d
--- /dev/null
+++ b/pin_control/pin_control.c
@@ -0,0 +1,102 @@
+#include <stdio.h>
+#include <gpiod.h>
+
+#define GPIO_CHIP "gpiochip0"
+
+struct gpiod_chip *chip;
+
+int init_gpio() {
+    // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_chip_open_by_name.html
+    chip = gpiod_chip_open_by_name(GPIO_CHIP);
+    if (!chip) {
+        printf("Error opening GPIO chip");
+        return -1;
+    }
+    return 0;
+}
+
+void cleanup_gpio() {
+    // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_chip_close.html
+    gpiod_chip_close(chip);
+}
+
+int set_pin_state(int pin, int state) {
+    // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_chip_get_line.html
+    struct gpiod_line *line = gpiod_chip_get_line(chip, pin);   // this may need an offset
+    if (!line) {
+        printf("Error getting GPIO line");
+        return -1;
+    }
+
+    // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_line_request_output.html
+    if (gpiod_line_request_output(line, "house-leds", state) < 0) {
+        printf("Error setting GPIO line direction");
+        gpiod_line_release(line);
+        return -1;
+    }
+
+    // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_line_set_value.html
+    if (gpiod_line_set_value(line, state) < 0) {
+        printf("Error setting GPIO line value");
+        gpiod_line_release(line);
+        return -1;
+    }
+
+    // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_line_release.html
+    gpiod_line_release(line);
+    return 0;
+}
+
+int read_button(int pin) {
+    // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_chip_get_line.html
+    struct gpiod_line *line = gpiod_chip_get_line(chip, pin + PIN_OFFSET);
+    if (!line) {
+        printf("Error getting GPIO line");
+        return -1;
+    }
+
+    // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_line_request_input.html
+    if (gpiod_line_request_input(line, "house-leds") < 0) {
+        printf("Error setting GPIO line direction to input");
+        gpiod_line_release(line);
+        return -1;
+    }
+
+    // https://libgpiod-dlang.dpldocs.info/gpiod.gpiod_line_get_value.html
+    int value = gpiod_line_get_value(line);
+    gpiod_line_release(line);
+    return value; // either 0 or 1
+}
+
+int turn_on_pin(int pin) {
+    return set_pin_state(pin, 1);
+}
+
+int turn_off_pin(int pin) {
+    return set_pin_state(pin, 0);
+}
+
+int turn_on_all_pins() {
+    for (int pin = 0; pin <= 5; pin++) {
+        if (turn_on_pin(pin) < 0)
+            return -1;
+    }
+    return 0;
+}
+
+int turn_off_all_pins() {
+    for (int pin = 0; pin <= 5; pin++) {
+        if (turn_off_pin(pin) < 0)
+            return -1;
+    }
+    return 0;
+}
+
+int wait_for_button_press(int button_pin) {
+    while (1) {
+        int button_state = read_button(button_pin); // maybe make it so that this works with a range of pins instead of just one
+        if (button_state == 1) {
+            return button_pin;
+        }
+    }
+}
diff --git a/pin_control/pin_control.h b/pin_control/pin_control.h
new file mode 100644
index 0000000..bcf2dc7
--- /dev/null
+++ b/pin_control/pin_control.h
@@ -0,0 +1,22 @@
+#ifndef GPIO_CONTROL_H
+#define GPIO_CONTROL_H
+
+int init_gpio();
+
+void cleanup_gpio();
+
+int set_pin_state(int pin, int state);
+
+int read_button(int pin);
+
+int turn_on_pin(int pin);
+
+int turn_off_pin(int pin);
+
+int turn_on_all_pins();
+
+int turn_off_all_pins();
+
+int wait_for_button_press(int button_pin);
+
+#endif /* GPIO_CONTROL_H */
diff --git a/pin_control/readme.md b/pin_control/readme.md
new file mode 100644
index 0000000..5f8c1ca
--- /dev/null
+++ b/pin_control/readme.md
@@ -0,0 +1 @@
+gcc -o pin_contro_test main.c pin_control.c -lgpiod
\ No newline at end of file