From 0e27f675ddbe239b27f1fa7251dd3900e1c02cff Mon Sep 17 00:00:00 2001
From: Savanni D'Gerinel <savanni@luminescent-dreams.com>
Date: Sat, 25 Jun 2022 23:35:14 -0400
Subject: [PATCH] Add functions to work with a 74HC595 shift register

---
 shift_register/reg.c | 27 +++++++++++++++++++++++++++
 shift_register/reg.h | 15 +++++++++++++++
 2 files changed, 42 insertions(+)
 create mode 100644 shift_register/reg.c
 create mode 100644 shift_register/reg.h

diff --git a/shift_register/reg.c b/shift_register/reg.c
new file mode 100644
index 0000000..ba23d75
--- /dev/null
+++ b/shift_register/reg.c
@@ -0,0 +1,27 @@
+#include <base.h>
+#include <reg.h>
+
+void shift_register_initialize(shift_register_t *reg) {
+    set_line_direction(&reg->output, LINE_OUT);
+    set_line_direction(&reg->shift_clock, LINE_OUT);
+    set_line_direction(&reg->latch_clock, LINE_OUT);
+
+    clear_line(&reg->output);
+    clear_line(&reg->shift_clock);
+    clear_line(&reg->latch_clock);
+}
+
+void send_byte_lsb(shift_register_t *reg, uint8_t byte) {
+    for (uint8_t i = 0; i < 8; i++) {
+        byte & _BV(i) ? set_line(&reg->output) : clear_line(&reg->output);
+        strobe_line(&reg->shift_clock);
+    }
+}
+
+void shift_out(shift_register_t *reg, uint8_t byte) {
+    send_byte_lsb(reg, byte);
+    clear_line(&reg->output);
+    strobe_line(&reg->latch_clock);
+}
+
+
diff --git a/shift_register/reg.h b/shift_register/reg.h
new file mode 100644
index 0000000..1d92b34
--- /dev/null
+++ b/shift_register/reg.h
@@ -0,0 +1,15 @@
+
+#ifndef __REG_H__
+#define __REG_H__
+
+typedef struct SHIFT_REGISTER {
+    gpio_t output;
+    gpio_t shift_clock;
+    gpio_t latch_clock;
+} shift_register_t;
+
+
+void shift_register_initialize(shift_register_t *reg);
+void shift_out(shift_register_t *reg, uint8_t byte);
+
+#endif