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The segment buffering code below possibly overwrites memory outside of the array bounds, in case of i = 7

hi,
i am new on GitHub. I downloaded the zip file but i can not find a xtm1638.h file in the zip file.
maybe I do something wrong?

wbr
Günter

The compiler (rightfully) complains about re-definition of these macros in the header file. The second definition overrides the first one. Unfortunately the two definitions use different value, so i'm wondering if the functions setNumber() and setSignedNumber() really do what they should.

Hi,
thanks for creating this cool library - it is the fastest one i found so far 👍

One idea to make it even faster would be to turn on higher compiler optimisations for the core functions, see https://gcc.gnu.org/onlinedocs/gcc/Function-Specific-Option-Pragmas.html
I did some experiments, by adding the following to xtm1638.cpp

at the top of the file, just after comments and includes are done (i.e. , directly after #include "xtm1638.h")

#pragma GCC push_options
#pragma GCC optimize ("O2")
//#pragma GCC optimize ("O3")

at end of the file

#pragma GCC pop_options

Testcase:

"example04" on my MEGA2560 - default options, Port manipulation mode, cached segments enabled

0. normal optimization without pragma:

• program 4440 Bytes (1%), glabal data 298 Bytes (3%)
• scores = 60003 (with LEDs), 27204 (no LEDs)

1. more optimization (-O2):

• program 4492 Bytes (1%), glabal data 298 bytes (3%) -> FLASH usage increase: 52 bytes
• scores = 26143 (with LEDs), 15102 (no LEDs) -> speed gain: 2.3x / 1.8x

2. even more optimization (-O3):

• program 13402 Bytes (5%), glabal data 298 bytes (3%) -> FLASH usage increase: 9 Kbytes
• scores = 24103 (with LEDs), 15280 (no LEDs) -> speed gain: 2.5x / 1.8x

While using setChars I've notice that "." is displayed as three horizontal bars. For example setChars("32.1") displays 32(3 horizontal bars)1 instead of 32.1
It would be nice if the dot was displayed as a dot on the same segment digit 2 in my example.

Such a fix would make displaying decimal number very easy, or do you already have a way to do this?

P.S. this is a great library and very impressive as far as speed is concerned. And the examples are A++.