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Added implementations of strchr, strcspn and strspn

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This commit is contained in:
Tom Almeida
2018-03-10 22:58:35 +08:00
parent b52a1d612d
commit 18283feac1
6 changed files with 96 additions and 6 deletions
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src/string/src/lib.rs
+61 -6
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@@ -90,8 +90,19 @@ pub unsafe extern "C" fn strcat(s1: *mut c_char, s2: *const c_char) -> *mut c_ch
}
#[no_mangle]
pub extern "C" fn strchr(s: *const c_char, c: c_int) -> *mut c_char {
unimplemented!();
pub unsafe extern "C" fn strchr(s: *const c_char, c: c_int) -> *mut c_char {
let c = c as i8;
let mut i = 0;
loop {
let cur = *s.offset(i);
if cur == c {
return s.offset(i) as *mut c_char;
}
if cur == 0 {
return ptr::null_mut();
}
i += 1;
}
}
#[no_mangle]
@@ -110,8 +121,30 @@ pub unsafe extern "C" fn strcpy(s1: *mut c_char, s2: *const c_char) -> *mut c_ch
}
#[no_mangle]
pub extern "C" fn strcspn(s1: *const c_char, s2: *const c_char) -> c_ulong {
unimplemented!();
pub unsafe extern "C" fn strcspn(s1: *const c_char, s2: *const c_char) -> c_ulong {
use core::mem;
let s1 = s1 as *const u8;
let s2 = s2 as *const u8;
// The below logic is effectively ripped from the musl implementation
let mut byteset = [0u8; 32/mem::size_of::<usize>()];
let mut i = 0;
while *s2.offset(i) != 0 {
byteset[(*s2.offset(i) as usize)/(8*mem::size_of::<usize>())] |= 1 << (*s2.offset(i) as usize % (8*mem::size_of::<usize>()));
i += 1;
}
i = 0; // reset
while *s2.offset(i) != 0 {
if byteset[(*s2.offset(i) as usize)/(8*mem::size_of::<usize>())] & 1 << (*s2.offset(i) as usize % (8*mem::size_of::<usize>())) > 0 {
break;
}
i += 1;
}
i as u64
}
#[no_mangle]
@@ -228,8 +261,30 @@ pub extern "C" fn strrchr(s: *const c_char, c: c_int) -> *mut c_char {
}
#[no_mangle]
pub extern "C" fn strspn(s1: *const c_char, s2: *const c_char) -> c_ulong {
unimplemented!();
pub unsafe extern "C" fn strspn(s1: *const c_char, s2: *const c_char) -> c_ulong {
use core::mem;
let s1 = s1 as *const u8;
let s2 = s2 as *const u8;
// The below logic is effectively ripped from the musl implementation
let mut byteset = [0u8; 32/mem::size_of::<usize>()];
let mut i = 0;
while *s2.offset(i) != 0 {
byteset[(*s2.offset(i) as usize)/(8*mem::size_of::<usize>())] |= 1 << (*s2.offset(i) as usize % (8*mem::size_of::<usize>()));
i += 1;
}
i = 0; // reset
while *s2.offset(i) != 0 {
if byteset[(*s2.offset(i) as usize)/(8*mem::size_of::<usize>())] & 1 << (*s2.offset(i) as usize % (8*mem::size_of::<usize>())) < 1 {
break;
}
i += 1;
}
i as u64
}
#[no_mangle]