feat(esp_hw_support): add esp_random() bit balance 0/1 ratio with sleep test case

components/esp_hw_support/test_apps/esp_hw_support_unity_tests/main/test_random.c

@@ -1,13 +1,24 @@
 /*
- * SPDX-FileCopyrightText: 2021-2022 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2021-2025 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
 #include <stdio.h>
 #include <string.h>
+#include <math.h>
+#include <inttypes.h>
+#include "sdkconfig.h"
+#include "soc/soc_caps.h"
 #include "unity.h"
 #include "esp_random.h"
 
+#if SOC_LIGHT_SLEEP_SUPPORTED
+#include "esp_sleep.h"
+#include "esp_private/esp_sleep_internal.h"
+#include "esp_private/sleep_cpu.h"
+#include "esp_private/esp_pmu.h"
+#endif
+
 /* Note: these are just sanity tests, not the same as
    entropy tests
 */
@@ -69,3 +80,57 @@ TEST_CASE("call esp_fill_random()", "[random]")
         TEST_ASSERT_EQUAL_HEX8(0xFF, one_buf[x]);
     }
 }
+
+TEST_CASE("verify esp_random() bit balance 0/1 ratio", "[random]")
+{
+#if SOC_LIGHT_SLEEP_SUPPORTED
+    esp_sleep_context_t sleep_ctx;
+    esp_sleep_set_sleep_context(&sleep_ctx);
+    printf("go to light sleep for 1 seconds\r\n");
+#if CONFIG_PM_ESP_SLEEP_POWER_DOWN_CPU
+    TEST_ESP_OK(sleep_cpu_configure(true));
+#endif
+    TEST_ESP_OK(esp_sleep_enable_timer_wakeup(1 * 1000 * 1000));
+    TEST_ESP_OK(esp_light_sleep_start());
+#if CONFIG_PM_POWER_DOWN_PERIPHERAL_IN_LIGHT_SLEEP && !SOC_PM_TOP_PD_NOT_ALLOWED
+    // check if the power domain also is powered down
+    TEST_ASSERT_EQUAL(PMU_SLEEP_PD_TOP, (sleep_ctx.sleep_flags) & PMU_SLEEP_PD_TOP);
+#endif
+    esp_sleep_set_sleep_context(NULL);
+    printf("Waked up! Let's see if esp_random can still work correctly...\r\n");
+#if CONFIG_PM_ESP_SLEEP_POWER_DOWN_CPU
+    TEST_ESP_OK(sleep_cpu_configure(false));
+#endif
+#endif
+
+    const size_t NUM_RANDOM = 50000; /* Need enough samples for statistical significance */
+    const float EXPECTED_RATIO = 0.5f; /* Expected ratio of 1s */
+    const float TOLERANCE = 0.01f; /* Allow 1% deviation (49%-51%) */
+    uint32_t bit_counts[32] = {0}; /* Count of 1s for each bit position */
+    /* Collect random numbers and count 1s in each bit position */
+    for (int i = 0; i < NUM_RANDOM; i++) {
+        uint32_t r = esp_random();
+        for (int bit = 0; bit < 32; bit++) {
+            if (r & (1U << bit)) {
+                bit_counts[bit]++;
+            }
+        }
+    }
+    /* Verify each bit position has approximately 50% ones */
+    printf("\nBit balance statistics (total samples: %zu):\n", NUM_RANDOM);
+    printf("Bit | 1s count | 0s count | 1s ratio | 0s ratio | Deviation\n");
+    printf("----|----------|----------|----------|----------|----------\n");
+    for (int bit = 0; bit < 32; bit++) {
+        uint32_t ones_count = bit_counts[bit];
+        uint32_t zeros_count = NUM_RANDOM - ones_count;
+        float ratio_ones = (float)ones_count / NUM_RANDOM;
+        float ratio_zeros = (float)zeros_count / NUM_RANDOM;
+        float deviation = fabs(ratio_ones - EXPECTED_RATIO);
+
+        printf("%3d | %8" PRIu32 " | %8" PRIu32 " | %8.4f | %8.4f | %9.4f\n",
+               bit, ones_count, zeros_count, ratio_ones, ratio_zeros, deviation);
+
+        /* Check if ratio is within tolerance */
+        TEST_ASSERT_LESS_THAN_FLOAT(TOLERANCE, deviation);
+    }
+}

components/esp_hw_support/test_apps/esp_hw_support_unity_tests/sdkconfig.ci.release

@@ -4,3 +4,5 @@ CONFIG_BOOTLOADER_COMPILER_OPTIMIZATION_SIZE=y
 
 # we can silent the assertion to save the binary footprint
 CONFIG_COMPILER_OPTIMIZATION_ASSERTIONS_SILENT=y
+
+CONFIG_PM_POWER_DOWN_PERIPHERAL_IN_LIGHT_SLEEP=y

components/esp_hw_support/test_apps/esp_hw_support_unity_tests/sdkconfig.defaults

@@ -6,3 +6,6 @@ CONFIG_BOOTLOADER_COMPILER_OPTIMIZATION_SIZE=y
 
 # we can silent the assertion to save the binary footprint
 CONFIG_COMPILER_OPTIMIZATION_ASSERTIONS_SILENT=y
+
+# primitives for checking sleep internal state
+CONFIG_ESP_SLEEP_DEBUG=y