I was trying to create an equation that told me how many flash blocks (pages) it would take to store some data I need. This may take up exactly a certain number of Flash blocks (pages), but more likely there will be spillover and part of (well, all of) another flash block will be needed. The C preprocessor gives wrong calculations for 2 of the three methods I have tried. All 3 methods work on Compiler Explorer and the freebie IDE that comes from the chip manufacturer. Maybe there is something I am doing wrong, but so far it escapes me. Is this possibly a compiler bug?
// From stm32f1xx_hal_flash_ex.h: // #define FLASH_PAGE_SIZE 0x400U // From my code: **Choose only one of the NUM_ITEMS** #define ITEM_SIZE 224UL #define NUM_ITEMS 64 // 64*224=14336 : 14 flash blocks #define NUM_ITEMS 66 // 66*224=14784 : 14.44 --> 15 flash blocks // ORIGINAL MACRO: DOES NOT WORK. ALWAYS GIVES 14 #define BLOCKS_FULL ((NUM_ITEMS*ITEM_SIZE)/FLASH_PAGE_SIZE) #define REMAINDER ((NUM_ITEMS*ITEM_SIZE)%FLASH_PAGE_SIZE) #if REMAINDER == 0 #define NUM_BLOCKS1 BLOCKS_FULL #else #define NUM_BLOCKS1 (BLOCKS_FULL+1) // Partial extra block #endif // ALTERNATE MACRO 1: OK (14 or 15) #define NUM_BLOCKS2 (((NUM_ITEMS*ITEM_SIZE) + (FLASH_PAGE_SIZE-1)) / FLASH_PAGE_SIZE) // ALTERNATE MACRO 2: NOPE, SAME ISSUE AS ORIG? ALWAYS GIVES 14 #define FLASH_TOTAL (NUM_ITEMS*ITEM_SIZE) #define FLASH_BLOCKS (FLASH_TOTAL/FLASH_PAGE_SIZE) #if FLASH_TOTAL == (FLASH_BLOCKS * FLASH_PAGE_SIZE) #define NUM_BLOCKS3 FLASH_BLOCKS #else #define NUM_BLOCKS3 (FLASH_BLOCKS+1) #endif