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sf/cmif: optimize dispatch table walk to use binary search over linear search

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This commit is contained in:
Michael Scire 2021-12-06 13:13:46 -08:00
parent 1019bc54e6
commit 09c6aa29dd
3 changed files with 110 additions and 22 deletions
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75
libraries/libstratosphere/source/sf/cmif/sf_cmif_service_dispatch.cpp
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@ -17,6 +17,65 @@
namespace ams::sf::cmif {
namespace {
ALWAYS_INLINE decltype(ServiceCommandMeta::handler) FindCommandHandlerByBinarySearch(const ServiceCommandMeta *entries, const size_t entry_count, const u32 cmd_id, const hos::Version hos_version) {
/* Binary search for the handler. */
ssize_t lo = 0;
ssize_t hi = entry_count - 1;
while (lo <= hi) {
const size_t mid = (lo + hi) / 2;
if (entries[mid].cmd_id < cmd_id) {
lo = mid + 1;
} else if (entries[mid].cmd_id > cmd_id) {
hi = mid - 1;
} else {
/* Find start. */
size_t start = mid;
while (start > 0 && entries[start - 1].cmd_id == cmd_id) {
--start;
}
/* Find end. */
size_t end = mid + 1;
while (end < entry_count && entries[end].cmd_id == cmd_id) {
++end;
}
for (size_t idx = start; idx < end; ++idx) {
if (entries[idx].MatchesVersion(hos_version)) {
return entries[idx].GetHandler();
}
}
break;
}
}
return nullptr;
}
ALWAYS_INLINE decltype(ServiceCommandMeta::handler) FindCommandHandlerByLinearSearch(const ServiceCommandMeta *entries, const size_t entry_count, const u32 cmd_id, const hos::Version hos_version) {
for (size_t i = 0; i < entry_count; ++i) {
if (entries[i].Matches(cmd_id, hos_version)) {
return entries[i].GetHandler();
break;
}
}
return nullptr;
}
ALWAYS_INLINE decltype(ServiceCommandMeta::handler) FindCommandHandler(const ServiceCommandMeta *entries, const size_t entry_count, const u32 cmd_id, const hos::Version hos_version) {
if (entry_count >= 8) {
return FindCommandHandlerByBinarySearch(entries, entry_count, cmd_id, hos_version);
} else {
return FindCommandHandlerByLinearSearch(entries, entry_count, cmd_id, hos_version);
}
}
}
Result impl::ServiceDispatchTableBase::ProcessMessageImpl(ServiceDispatchContext &ctx, const cmif::PointerAndSize &in_raw_data, const ServiceCommandMeta *entries, const size_t entry_count) const {
/* Get versioning info. */
const auto hos_version = hos::GetVersion();
@ -30,13 +89,7 @@ namespace ams::sf::cmif {
const u32 cmd_id = in_header->command_id;
/* Find a handler. */
decltype(ServiceCommandMeta::handler) cmd_handler = nullptr;
for (size_t i = 0; i < entry_count; i++) {
if (entries[i].Matches(cmd_id, hos_version)) {
cmd_handler = entries[i].GetHandler();
break;
}
}
const auto cmd_handler = FindCommandHandler(entries, entry_count, cmd_id, hos_version);
R_UNLESS(cmd_handler != nullptr, sf::cmif::ResultUnknownCommandId());
/* Invoke handler. */
@ -73,13 +126,7 @@ namespace ams::sf::cmif {
const u32 cmd_id = in_header->command_id;
/* Find a handler. */
decltype(ServiceCommandMeta::handler) cmd_handler = nullptr;
for (size_t i = 0; i < entry_count; i++) {
if (entries[i].Matches(cmd_id, hos_version)) {
cmd_handler = entries[i].GetHandler();
break;
}
}
const auto cmd_handler = FindCommandHandler(entries, entry_count, cmd_id, hos_version);
/* If we didn't find a handler, forward the request. */
if (cmd_handler == nullptr) {