使用C语言从M68k内存地址获取特定的十六进制

Question

I've got a new question related to this other one, which is solved Get specific byte from M68k ram address with C language

Now my address has a full row of:

FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF

which are hexadecimals.

If I tried with the same pattern of the other question, I can't get the value displayed by printf... this is what I've done:

char* REG_SW;
REG_SW = (char*)0x300123;

then:

printf("H DIP SWITCHES:  %d",   REG_SW[0])

gives me -1

Thanks in advance and Merry XMas!!

Answer 1

In order to print the char value in hex form use

printf("H DIP SWITCHES:  %02X",   REG_SW[0])

Look here for printf tutorial, but the essence in our case is using the X format specifier having value printed in hex form 2 bytes wide (this is what behind the format width 02 )

EDIT- as chux observed in his comment to the question its crucial treating the register value as an unsigned type one

unsigned char* REG_SW (unsigned char*) 0x300123;