Hi,
Just noticed an odd behavior of sprintf / snprintf functions, and probably
all other functions using va_list() as well.
Function parameters are pushed to the stack but never popped back, so the
stack gets occupied with junk. I tried to rebuild the libc
with -O2, -O1, -O0 but that did not make any change. I am using the
msp430f169 and the latest win32 MSPGCC binary build on the website.
Here is the disassembly of a sample program with -O1. After the last call,
stack has 6 unwelcome words more.
199 (void)sprintf(str, "str 1 %d 2 %d 3 %d 4 %d", 1, 2, 3, 4);
0x3c7a <main+30>: push #4 ;#0x0004
- 0x3c7e <main+34>: push #3 ;#0x0003
- 0x3c82 <main+38>: push #2 ;subst r3 with As==10
0x3c84 <main+40>: push #1 ;subst r3 with As==01
- 0x3c86 <main+42>: push #15428 ;#0x3c44
- 0x3c8a <main+46>: push r4 ;
- 0x3c8c <main+48>: call #31994 ;#0x7cfa
Here is the same piece, but with -O0. Note the add #14 at the end.
199 (void)snprintf(str, 30, "str 1 %d 2 %d 3 %d 4 %d", 1, 2, 3, 4);
0x4970 <main+44>: push #4 ;#0x0004
- 0x4974 <main+48>: push #3 ;#0x0003
- 0x4978 <main+52>: push #2 ;subst r3 with As==10
- 0x497a <main+54>: push #1 ;subst r3 with As==01
- 0x497c <main+56>: push #18732 ;#0x492c
- 0x4980 <main+60>: push #30 ;#0x001e
- 0x4984 <main+64>: push r4 ;
- 0x4986 <main+66>: call #-26478 ;#0x9892
- 0x498a <main+70>: add #14, SP ;#0x000e
/Andrei
