From 60bd03a5178e338b04703783a686d9c73633ba63 Mon Sep 17 00:00:00 2001
From: George Talusan <george.talusan@gmail.com>
Date: Sat, 27 Feb 2016 11:41:39 -0500
Subject: [PATCH] be quicker about determining erased byte pattern when
 flashing

---
 gdbserver/gdb-server.c |  2 +-
 src/stlink-common.c    | 18 ++++++++++--------
 src/stlink-common.h    |  2 +-
 3 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/gdbserver/gdb-server.c b/gdbserver/gdb-server.c
index 0c31cff..ef289f2 100644
--- a/gdbserver/gdb-server.c
+++ b/gdbserver/gdb-server.c
@@ -752,7 +752,7 @@ static int flash_go(stlink_t *sl) {
             DLOG("flash_do: page %08x\n", page);
             unsigned send = length > FLASH_PAGE ? FLASH_PAGE : length;
             if(stlink_write_flash(sl, page, fb->data + (page - fb->addr),
-                        send) < 0)
+                        send, 0) < 0)
                 goto error;
             length -= send;
             
diff --git a/src/stlink-common.c b/src/stlink-common.c
index 90d71f3..917a1e0 100644
--- a/src/stlink-common.c
+++ b/src/stlink-common.c
@@ -1723,7 +1723,7 @@ int stm32l1_write_half_pages(stlink_t *sl, stm32_addr_t addr, uint8_t* base, uin
     return 0;
 }
 
-int stlink_write_flash(stlink_t *sl, stm32_addr_t addr, uint8_t* base, uint32_t len) {
+int stlink_write_flash(stlink_t *sl, stm32_addr_t addr, uint8_t* base, uint32_t len, uint8_t eraseonly) {
     size_t off;
     flash_loader_t fl;
     ILOG("Attempting to write %d (%#x) bytes to stm32 address: %u (%#x)\n",
@@ -1769,6 +1769,9 @@ int stlink_write_flash(stlink_t *sl, stm32_addr_t addr, uint8_t* base, uint32_t
     ILOG("Finished erasing %d pages of %d (%#x) bytes\n",
             page_count, sl->flash_pgsz, sl->flash_pgsz);
 
+    if (eraseonly)
+        return 0;
+
     if ((sl->chip_id == STM32_CHIPID_F2) ||
         (sl->chip_id == STM32_CHIPID_F4) ||
         (sl->chip_id == STM32_CHIPID_F4_DE) ||
@@ -1972,19 +1975,18 @@ int stlink_fwrite_flash(stlink_t *sl, const char* path, stm32_addr_t addr) {
         ELOG("map_file() == -1\n");
         return -1;
     }
-    for(index = 0; index < mf.len; index ++) {
-        if (mf.base[index] == erased_pattern)
-            num_empty ++;
-        else
-            num_empty = 0;
+    for(index = mf.len - 1; num_empty < mf.len; index --) {
+        if (mf.base[index] != erased_pattern) {
+            break;
+        }
+        num_empty ++;
     }
     /* Round down to words */
     num_empty -= (num_empty & 3);
     if(num_empty != 0) {
         ILOG("Ignoring %d bytes of 0x%02x at end of file\n", num_empty, erased_pattern);
-        mf.len -= num_empty;
     }
-    err = stlink_write_flash(sl, addr, mf.base, mf.len);
+    err = stlink_write_flash(sl, addr, mf.base, num_empty == mf.len? mf.len : mf.len - num_empty, num_empty == mf.len);
     /* set stack*/
     stlink_write_reg(sl, stlink_read_debug32(sl, addr    ),13);
     /* Set PC to the reset routine*/
diff --git a/src/stlink-common.h b/src/stlink-common.h
index a0bd649..2751ac8 100644
--- a/src/stlink-common.h
+++ b/src/stlink-common.h
@@ -655,7 +655,7 @@ extern "C" {
 
     // unprocessed
     int stlink_erase_flash_mass(stlink_t* sl);
-    int stlink_write_flash(stlink_t* sl, stm32_addr_t address, uint8_t* data, uint32_t length);
+    int stlink_write_flash(stlink_t* sl, stm32_addr_t address, uint8_t* data, uint32_t length, uint8_t eraseonly);
     int stlink_fwrite_flash(stlink_t *sl, const char* path, stm32_addr_t addr);
     int stlink_fwrite_sram(stlink_t *sl, const char* path, stm32_addr_t addr);
     int stlink_verify_write_flash(stlink_t *sl, stm32_addr_t address, uint8_t *data, uint32_t length);
-- 
2.47.2