I'm using 80c390 in 24-bit mode (a TINI board). If I define the following: struct rtc { unsigned char seconds; unsigned char minutes; unsigned char hours; } struct rtc *p_time; I have a pointer (p_time), which is located somewhere in XDATA ( > 0x100080) and it points to address I:0x00 and there messes up with register bank0. If I declare the pointer as struct rtc * xdata p_time; it points to X:0x000000. What am I doing wrong? Val
Even worse: that all-zeros pointer will trash your registers. In hindsight, I'd wish for a different mapping for that tag byte. (Say 0-7fh is xdata, without having to subtract one to get the bank; high values can map to code and idata/data.) But changing now would introduce a fairly major incompatibility with existing code, and annoy everyone that wrote assembler routines that have an interface with a C pointer involved.