xobs/simmel-bootloader
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Use local variable to store partially-calculated size.

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This avoid re-entrancy problems, such as if this is ever
interrupted mid-execution, and called a second time before
the initial execution completes.
This commit is contained in:
Henry Gabryjelski 2019-03-12 13:41:33 -07:00
parent 4ea74d4600
commit b8a0551678
1 changed files with 9 additions and 7 deletions
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16
src/usb/uf2/ghostfat.c
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@ -123,35 +123,37 @@ static FAT_BootBlock const BootBlock = {
static uint32_t current_flash_size(void) static uint32_t current_flash_size(void)
{ {
static uint32_t flash_sz = 0; static uint32_t flash_sz = 0;
uint32_t result = flash_sz; // presumes atomic 32-bit read/write and static result
// only need to compute once // only need to compute once
if ( flash_sz == 0 ) if ( result == 0 )
{ {
// return 1 block of 256 bytes // return 1 block of 256 bytes
if ( !bootloader_app_is_valid(DFU_BANK_0_REGION_START) ) if ( !bootloader_app_is_valid(DFU_BANK_0_REGION_START) )
{ {
flash_sz = 256; result = 256;
}else }else
{ {
bootloader_settings_t const * boot_setting; bootloader_settings_t const * boot_setting;
bootloader_util_settings_get(&boot_setting); bootloader_util_settings_get(&boot_setting);
flash_sz = boot_setting->bank_0_size; result = boot_setting->bank_0_size;
// Copy size must be multiple of 256 bytes // Copy size must be multiple of 256 bytes
// else we will got an issue copying current.uf2 // else we will got an issue copying current.uf2
if (flash_sz & 0xff) if (result & 0xff)
{ {
flash_sz = (flash_sz & ~0xff) + 256; result = (result & ~0xff) + 256;
} }
// if bank0 size is not valid, happens when flashed with jlink // if bank0 size is not valid, happens when flashed with jlink
// use maximum application size // use maximum application size
if ( (flash_sz == 0) || (flash_sz == 0xFFFFFFFFUL) ) if ( (result == 0) || (result == 0xFFFFFFFFUL) )
{ {
flash_sz = FLASH_SIZE; result = FLASH_SIZE;
} }
} }
flash_sz = result; // presumes atomic 32-bit read/write and static result
} }
return flash_sz; return flash_sz;