Replace multiplication with division for microseconds calculation from
nanoseconds in _gettimeofday function.
Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
- RISC-V 32 bits linux/glibc didn't provide gettimeofday anymore
after upstream, because RV32 didn't have backward compatible issue,
so RV32 only support 64 bits time related system call.
- So using clock_gettime64 call instead for rv32 libgloss.
Previously, __internal_syscall() compiled into asm-code that unconditionally
sets the syscall argument registers a0 to a5.
For example, the instruction sequence for a exit syscall looked like
this:
li a0, 1 # in ther caller of exit()
# ... # in newlib:
li a1, 0 # unused arguments
li a2, 0
li a3, 0
li a4, 0
li a5, 0
li a7, 93 # exit syscall number
(i.e. the binary contains then 5 superfluous instructions for this
one argument syscall)
This commit changes the RISC-V syscall code such that only the required
syscall argument registers are set.
GCC detects that argc is known at compile time and thus evaluates all the
if-statements where argc is used at compile time (tested with -O2 and -Os).
Kuan-Wei Chiu
Kito Cheng
Georg Sauthoff
Jim Wilson