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Add comments and tiny improvements to STM32 flash loader algorithm

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Add comments to assembly flash loader for STM32. Add tiny improvement in
size of the algorithm (40 vs 48 bytes) and tiny speed improvement (~1.5%,
as time is wasted on waiting for end of operation anyway).

Signed-off-by: Freddie Chopin <freddie_chopin@op.pl>
This commit is contained in:
Freddie Chopin
2010-11-13 15:42:00 +01:00
committed by Øyvind Harboe
parent 6287c23b32
commit 015bf55944
2 changed files with 42 additions and 37 deletions
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33
src/flash/nor/stm32x.c
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@@ -503,25 +503,26 @@ static int stm32x_write_block(struct flash_bank *bank, uint8_t *buffer,
/* see contib/loaders/flash/stm32x.s for src */
static const uint8_t stm32x_flash_write_code[] = {
/* #define STM32_FLASH_CR_OFFSET 0x10 */
/* #define STM32_FLASH_SR_OFFSET 0x0C */
/* write: */
0xDF, 0xF8, 0x24, 0x40, /* ldr r4, STM32_FLASH_CR */
0x09, 0x4D, /* ldr r5, STM32_FLASH_SR */
0x4F, 0xF0, 0x01, 0x03, /* mov r3, #1 */
0x23, 0x60, /* str r3, [r4, #0] */
0x30, 0xF8, 0x02, 0x3B, /* ldrh r3, [r0], #2 */
0x21, 0xF8, 0x02, 0x3B, /* strh r3, [r1], #2 */
0xdf, 0xf8, 0x20, 0x40, /* ldr r4, STM32_FLASH_BASE */
/* write_half_word: */
0x01, 0x23, /* movs r3, #0x01 */
0x23, 0x61, /* str r3, [r4, #STM32_FLASH_CR_OFFSET] */
0x30, 0xf8, 0x02, 0x3b, /* ldrh r3, [r0], #0x02 */
0x21, 0xf8, 0x02, 0x3b, /* strh r3, [r1], #0x02 */
/* busy: */
0x2B, 0x68, /* ldr r3, [r5, #0] */
0x13, 0xF0, 0x01, 0x0F, /* tst r3, #0x01 */
0xFB, 0xD0, /* beq busy */
0x13, 0xF0, 0x14, 0x0F, /* tst r3, #0x14 */
0x01, 0xD1, /* bne exit */
0x01, 0x3A, /* subs r2, r2, #1 */
0xED, 0xD1, /* bne write */
0xe3, 0x68, /* ldr r3, [r4, #STM32_FLASH_SR_OFFSET] */
0x13, 0xf0, 0x01, 0x0f, /* tst r3, #0x01 */
0xfb, 0xd0, /* beq busy */
0x13, 0xf0, 0x14, 0x0f, /* tst r3, #0x14 */
0x01, 0xd1, /* bne exit */
0x01, 0x3a, /* subs r2, r2, #0x01 */
0xf0, 0xd1, /* bne write_half_word */
/* exit: */
0x00, 0xBE, /* bkpt #0 */
0x10, 0x20, 0x02, 0x40, /* STM32_FLASH_CR: .word 0x40022010 */
0x0C, 0x20, 0x02, 0x40 /* STM32_FLASH_SR: .word 0x4002200C */
0x00, 0xbe, /* bkpt #0x00 */
0x00, 0x20, 0x02, 0x40, /* STM32_FLASH_BASE: .word 0x40022000 */
};
/* flash write code */