This is an idea that I don't want distracting me until I'm done with my current work on printf, so I'm spilling it to the mailing list.
A big limitation on printf right now is the size of the stack buffer to hold a formatted number. Adding 64-bit support means doubling that size. And if ROM space is to be hoarded like silver on a microcontroller, RAM space is gold. Would it be worth enlarging the code to store converted numbers in BCD? When printing hex, phase 1 would consist of counting significant digits, and phase 2 would do everything. Typical ATmega flash/SRAM size are 4K 0.25K/0.5K (48A/48PB) 8K 0.5K/1K (88A/88PB) 16K 1K (16A,164A,168A) 32K 2K (32,32[459],AT90CAN32) 64K 4K (64,64[045679],AT90CAN64) 128K 4K/8K/16K (128A,AT90CAN128/128[01]/1284) 256K 8K (256[01]) It seems like SRAM 1/16 the size of program ROM is the most common configuration. So 11 bytes of stack could be considered "worth" 88 instructions. _______________________________________________ AVR-libc-dev mailing list AVR-libc-dev@nongnu.org https://lists.nongnu.org/mailman/listinfo/avr-libc-dev
