From e8591132d4885f603f32918f6f51c3ef91b57b33 Mon Sep 17 00:00:00 2001
From: Ryan <>
Date: Fri, 26 Sep 2025 18:42:39 -0500
Subject: [PATCH] Add autoerase to digdude

---
 .../nexys2_host_controller/host/digdude.c     | 121 ++++++++++++++++--
 1 file changed, 108 insertions(+), 13 deletions(-)

diff --git a/projects/nexys2_host_controller/host/digdude.c b/projects/nexys2_host_controller/host/digdude.c
index 135d73b..6a979d4 100644
--- a/projects/nexys2_host_controller/host/digdude.c
+++ b/projects/nexys2_host_controller/host/digdude.c
@@ -26,6 +26,112 @@ enum exitspec { X_RESET, X_NORESET };
 // -----------------------------------------------------------------------------
 
 
+typedef struct
+{
+	uint32_t block_size;
+	uint32_t block_count;
+	uint8_t  block_is_erased[0x10000];
+} erase_region_t;
+
+
+typedef struct
+{
+	uint8_t        region_count;
+	erase_region_t regions[256];
+} erase_info_t;
+
+
+static erase_info_t erase_info;
+
+
+bool get_erase_info(HIF hif)
+{
+	assert(hif != hifInvalid);
+
+	uint8_t cfi_buf[0x100];
+
+	// Read and verify CFI query information
+	EC_FALSE(flash_cfi(hif, 0, cfi_buf, sizeof(cfi_buf)));
+	EC_FALSE(cfi_buf[0x10] == 'Q');
+	EC_FALSE(cfi_buf[0x11] == 'R');
+	EC_FALSE(cfi_buf[0x12] == 'Y');
+
+	// Flash chips can contain multiple "erase regions," each of which
+	// contains some number of equal-sized eraseable blocks
+
+	// Read the number of regions from the CFI query and loop for each
+	erase_info.region_count = cfi_buf[0x2c];
+
+	for (size_t i = 0; i < erase_info.region_count; i++)
+	{
+		size_t block_info_idx = 0x2d + (4 * i);
+		assert(block_info_idx < 0x100);  // Just in case
+
+		// Read the geometry of this region's blocks from the CFI query
+		uint32_t block_count = ((cfi_buf[block_info_idx + 1] << 8) |
+		                         cfi_buf[block_info_idx + 0]) + 1;
+		uint32_t block_size  = ((cfi_buf[block_info_idx + 3] << 8) |
+		                         cfi_buf[block_info_idx + 2]) * 256;
+		if (block_size == 0) block_size = 128;
+
+		erase_info.regions[i].block_size  = block_size;
+		erase_info.regions[i].block_count = block_count;
+	}
+
+	return true;
+
+EC_CLEANUP_BEGIN
+	return false;
+EC_CLEANUP_END
+}
+
+
+bool ensure_erased(HIF hif, uint32_t addr, size_t data_len)
+{
+	assert(hif != hifInvalid);
+
+	uint32_t scan_addr = 0;
+
+	uint32_t region_count = erase_info.region_count;
+	for (uint32_t i = 0; i < region_count; i++)
+	{
+		uint32_t block_count = erase_info.regions[i].block_count;
+		for (uint32_t j = 0; j < block_count; j++)
+		{
+			uint32_t block_size  = erase_info.regions[i].block_size;
+			uint32_t block_start = scan_addr;
+			uint32_t block_end   = scan_addr + block_size;
+
+			uint32_t data_start  = addr;
+			uint32_t data_end    = data_start + data_len;
+
+			if (data_start < block_end && data_end > block_start)
+			{
+				if (!erase_info.regions[i].block_is_erased[j])
+				{
+					printf("Erase region:%u of %u, block:%u of %u, addr:%08x size:%08x\n",
+					       i+1, region_count,
+					       j+1, block_count,
+					       block_start, block_size);
+					EC_FALSE(flash_erase(hif, scan_addr));
+					erase_info.regions[i].block_is_erased[j] = 1;
+				}
+			}
+			scan_addr = block_end;
+		}
+	}
+
+	return true;
+
+EC_CLEANUP_BEGIN
+	return false;
+EC_CLEANUP_END
+}
+
+
+// -----------------------------------------------------------------------------
+
+
 bool update_ram_read(HIF hif, struct iter *iter, uint32_t addr, size_t data_len)
 {
 	assert(hif != hifInvalid);
@@ -178,25 +284,14 @@ bool update_flash_write(HIF hif, struct iter *iter, bool erase, bool verify)
 	assert(hif != hifInvalid);
 	assert(iter != NULL);
 
-	uint32_t unerased_watermark = 0;
-	uint8_t cfi_buf[0x100];
-	uint8_t num_erase_regions;
-
-	// Read and verify CFI query information
-	EC_FALSE(flash_cfi(hif, 0, cfi_buf, sizeof(cfi_buf)));
-	EC_FALSE(cfi_buf[0x10] == 'Q');
-	EC_FALSE(cfi_buf[0x11] == 'R');
-	EC_FALSE(cfi_buf[0x12] == 'Y');
-
-	// Read the number of regions from the CFI query and loop for each
-	num_erase_regions = cfi_buf[0x2c];
+	if (erase) EC_FALSE(get_erase_info(hif));
 
 	while (!iter_done(iter))
 	{
 		EC_FALSE(iter_next(iter));
 		if (erase)
 		{
-			// TODO
+			EC_FALSE(ensure_erased(hif, iter->address, iter->data_len));
 		}
 		EC_FALSE(flash_write(hif, iter->address, iter->data, iter->data_len));
 
-- 
2.43.0