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-rw-r--r--contrib/loaders/flash/stm32x.s40
1 files changed, 22 insertions, 18 deletions
diff --git a/contrib/loaders/flash/stm32x.s b/contrib/loaders/flash/stm32x.s
index dcf2b83c..6cf9f579 100644
--- a/contrib/loaders/flash/stm32x.s
+++ b/contrib/loaders/flash/stm32x.s
@@ -19,7 +19,10 @@
***************************************************************************/
.text
- .arm
+ .syntax unified
+ .thumb
+ .thumb_func
+ .global write
/*
r0 - source address
@@ -27,26 +30,27 @@
r2 - count (halfword-16bit)
r3 - result
r4 - temp
- r5 - temp
*/
+#define STM32_FLASH_CR_OFFSET 0x10 /* offset of CR register in FLASH struct */
+#define STM32_FLASH_SR_OFFSET 0x0c /* offset of CR register in FLASH struct */
+
write:
- ldr r4, STM32_FLASH_CR
- ldr r5, STM32_FLASH_SR
- mov r3, #1
- str r3, [r4, #0]
- ldrh r3, [r0], #2
- strh r3, [r1], #2
+ ldr r4, STM32_FLASH_BASE
+write_half_word:
+ movs r3, #0x01
+ str r3, [r4, #STM32_FLASH_CR_OFFSET] /* PG (bit0) == 1 => flash programming enabled */
+ ldrh r3, [r0], #0x02 /* read one half-word from src, increment ptr */
+ strh r3, [r1], #0x02 /* write one half-word from src, increment ptr */
busy:
- ldr r3, [r5, #0]
- tst r3, #0x01
- beq busy
- tst r3, #0x14
- bne exit
- subs r2, r2, #1
- bne write
+ ldr r3, [r4, #STM32_FLASH_SR_OFFSET]
+ tst r3, #0x01 /* BSY (bit0) == 1 => operation in progress */
+ beq busy /* wait more... */
+ tst r3, #0x14 /* PGERR (bit2) == 1 or WRPRTERR (bit4) == 1 => error */
+ bne exit /* fail... */
+ subs r2, r2, #0x01 /* decrement counter */
+ bne write_half_word /* write next half-word if anything left */
exit:
- bkpt #0
+ bkpt #0x00
-STM32_FLASH_CR: .word 0x40022010
-STM32_FLASH_SR: .word 0x4002200C
+STM32_FLASH_BASE: .word 0x40022000 /* base address of FLASH struct */