From 14bc823024bd92fd9f7acfead41aa542eef431ba Mon Sep 17 00:00:00 2001
From: logicog <git@logicog.de>
Date: Wed, 4 Mar 2026 20:19:46 +0100
Subject: [PATCH] Add reg_bit_test function

---
 rtl837x_common.h |  1 +
 rtlplayground.c  | 17 +++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/rtl837x_common.h b/rtl837x_common.h
index 8fe6764..c69d303 100644
--- a/rtl837x_common.h
+++ b/rtl837x_common.h
@@ -122,6 +122,7 @@ void print_reg(uint16_t reg);
 uint8_t sfp_read_reg(uint8_t slot, uint8_t reg);
 void reg_bit_set(uint16_t reg_addr, char bit);
 void reg_bit_clear(uint16_t reg_addr, char bit);
+uint8_t reg_bit_test(uint16_t reg_addr, char bit);
 void sfr_mask_data(uint8_t n, uint8_t mask, uint8_t set);
 void sfr_set_zero(void);
 void reset_chip(void);
diff --git a/rtlplayground.c b/rtlplayground.c
index 6a16e31..041c7ed 100644
--- a/rtlplayground.c
+++ b/rtlplayground.c
@@ -457,6 +457,23 @@ void reg_bit_clear(uint16_t reg_addr, char bit)
 	reg_write_m(reg_addr);
 }
 
+
+/*
+ * This sets a bit in the 32bit wide switch register reg_addr
+ */
+uint8_t reg_bit_test(uint16_t reg_addr, char bit)
+{
+	uint8_t bit_mask = 1 << (bit & 0x7);
+
+	bit >>= 3;
+	reg_read_m(reg_addr);
+	bit_mask = bit_mask;
+	if (sfr_data[3-bit] & bit_mask)
+		return 1;
+	return 0;
+}
+
+
 /*
  * This masks the sfr data fields, first &-ing with ~mask, then setting the bits in set
  */