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[libc][NFC] remove dependency on non standard ssize_t 

`ssize_t` is from POSIX and is not standard unfortunately.
Rewritting the code so it doesn't depend on it.

Differential Revision: https://reviews.llvm.org/D94760
This commit is contained in:
Guillaume Chatelet 2021-01-15 11:07:44 +00:00
parent d4bb3ef532
commit e517dff50a
1 changed files with 14 additions and 10 deletions
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24
libc/src/string/memmove.cpp
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@ -11,21 +11,25 @@
#include "src/stdlib/abs_utils.h" #include "src/stdlib/abs_utils.h"
#include "src/string/memcpy.h" #include "src/string/memcpy.h"
#include <stddef.h> // size_t, ptrdiff_t #include <stddef.h> // size_t, ptrdiff_t
#include <unistd.h> // ssize_t
namespace __llvm_libc { namespace __llvm_libc {
// src_m and dest_m might be the beginning or end. static inline void move_byte_forward(char *dest_m, const char *src_m,
static inline void move_byte(unsigned char *dest_m, const unsigned char *src_m, size_t count) {
size_t count, ssize_t direction) { for (size_t offset = 0; count; --count, ++offset)
for (ssize_t offset = 0; count; --count, offset += direction) dest_m[offset] = src_m[offset];
}
static inline void move_byte_backward(char *dest_m, const char *src_m,
size_t count) {
for (size_t offset = count - 1; count; --count, --offset)
dest_m[offset] = src_m[offset]; dest_m[offset] = src_m[offset];
} }
LLVM_LIBC_FUNCTION(void *, memmove, LLVM_LIBC_FUNCTION(void *, memmove,
(void *dest, const void *src, size_t count)) { (void *dest, const void *src, size_t count)) {
unsigned char *dest_c = reinterpret_cast<unsigned char *>(dest); char *dest_c = reinterpret_cast<char *>(dest);
const unsigned char *src_c = reinterpret_cast<const unsigned char *>(src); const char *src_c = reinterpret_cast<const char *>(src);
// If the distance between src_c and dest_c is equal to or greater // If the distance between src_c and dest_c is equal to or greater
// than count (integer_abs(src_c - dest_c) >= count), they would not overlap. // than count (integer_abs(src_c - dest_c) >= count), they would not overlap.
@ -50,11 +54,11 @@ LLVM_LIBC_FUNCTION(void *, memmove,
// src_c : [___abcde_] [_abcde___] // src_c : [___abcde_] [_abcde___]
// dest_c: [_abc--___] [___--cde_] // dest_c: [_abc--___] [___--cde_]
// TODO: Optimize `move_byte(...)` function. // TODO: Optimize `move_byte_xxx(...)` functions.
if (dest_c < src_c) if (dest_c < src_c)
move_byte(dest_c, src_c, count, /*pointer add*/ 1); move_byte_forward(dest_c, src_c, count);
if (dest_c > src_c) if (dest_c > src_c)
move_byte(dest_c + count - 1, src_c + count - 1, count, /*pointer add*/ -1); move_byte_backward(dest_c, src_c, count);
return dest; return dest;
} }