On 6/15/26 03:01, Gavin Shan wrote:
+void qemu_ram_copy(void *dest, const void *src, size_t n)
+{
+ if (HOST_UNALIGNED_MMIO_OK) {
+ switch (n) {
+ case 1:
+ __builtin_memcpy(dest, src, 1);
+ break;
+ case 2:
+ __builtin_memcpy(dest, src, 2);
+ break;
+ case 4:
+ __builtin_memcpy(dest, src, 4);
+ break;
+ case 8:
+ __builtin_memcpy(dest, src, 8);
+ break;
+ default:
+ memcpy(dest, src, n);
+ }
+ } else {
+ uintptr_t test, lsb;
+
+ do {
+ test = (uintptr_t)dest | n;
+ lsb = test & -test;
+ switch (lsb) {
Either assert n != 0 to start, or use while not do/while.
Because the body of the loop won't handle n == 0 correctly.
+ case 1:
+ *(uint8_t *)dest = *(uint8_t *)src;
+ src += 1;
+ dest += 1;
+ n -= 1;
+ break;
+ case 2:
+ *(uint16_t *)dest = *(uint16_t *)src;
+ src += 2;
+ dest += 2;
+ n -= 2;
+ break;
+ case 4:
+ *(uint32_t *)dest = *(uint32_t *)src;
+ src += 4;
+ dest += 4;
+ n -= 4;
+ break;
+ default:
+ *(uint64_t *)dest = *(uint64_t *)src;
+ src += 8;
+ dest += 8;
+ n -= 8;
Use qatomic_set for the stores.
src is not aligned, so except for case 1, you need ld{uw,l,q}_he_p.
+void qemu_ram_move(void *dest, const void *src, size_t n)
+{
+ if (HOST_UNALIGNED_MMIO_OK) {
+ switch (n) {
+ case 1:
+ __builtin_memmove(dest, src, 1);
+ break;
+ case 2:
+ __builtin_memmove(dest, src, 2);
+ break;
+ case 4:
+ __builtin_memmove(dest, src, 4);
+ break;
+ case 8:
+ __builtin_memmove(dest, src, 8);
+ break;
+ default:
+ memmove(dest, src, n);
+ }
+ } else {
+ qemu_ram_copy(dest, src, n);
+ }
+}
The qemu_ram_copy implementation above does not work with overlapping blocks.
r~
