Skip to content

Scattered mem access #125

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
eyck merged 2 commits into from
Apr 19, 2026
Merged

Scattered mem access #125

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
614bef6
implements #116
eyck Apr 19, 2026
215bf74
applies clang format, implements #118
eyck Apr 19, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
16 changes: 16 additions & 0 deletions src/common/util/ities.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,22 @@
#include <type_traits>
#include <vector>

#if defined(__GNUC__)
#ifndef LIKELY
#define LIKELY(x) ::__builtin_expect(!!(x), 1)
#endif
#ifndef UNLIKELY
#define UNLIKELY(x) ::__builtin_expect(!!(x), 0)
#endif
#else
#ifndef LIKELY
#define LIKELY(x) x
#endif
#ifndef UNLIKELY
#define UNLIKELY(x) x
#endif
#endif

#if __cplusplus < 201402L
#define CONSTEXPR
#else
Expand Down
47 changes: 31 additions & 16 deletions src/components/scc/memory.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@
#define _SYSC_MEMORY_H_

// Needed for the simple_target_socket
#include "util/ities.h"
#include <tlm/scc/memory_map_collector.h>
#include <tlm_core/tlm_2/tlm_generic_payload/tlm_gp.h>
#ifndef SC_INCLUDE_DYNAMIC_PROCESSES
Expand Down Expand Up @@ -244,16 +245,11 @@ int memory<SIZE, BUSWIDTH, PAGE_ADDR_BITS, USE_CYCLES>::handle_operation(tlm::tl
trans.set_response_status(tlm::TLM_GENERIC_ERROR_RESPONSE);
return 0;
}
if(byt) {
auto res = std::accumulate(byt, byt + trans.get_byte_enable_length(), 0xff, [](uint8_t a, uint8_t b) { return a | b; });
if(trans.get_byte_enable_length() != len || res != 0xff) {
SC_REPORT_ERROR("TLM-2", "generic payload transaction with scattered byte enable not supported");
trans.set_response_status(tlm::TLM_GENERIC_ERROR_RESPONSE);
return 0;
}
}
auto scattered =
byt ? std::accumulate(byt, byt + trans.get_byte_enable_length(), 0xff, [](uint8_t a, uint8_t b) { return a & b; }) != 0xff : false;
tlm::tlm_command cmd = trans.get_command();
SCCTRACE(SCMOD) << (cmd == tlm::TLM_READ_COMMAND ? "read" : "write") << " access to addr 0x" << std::hex << adr;
trans.set_dmi_allowed(allow_dmi.get_value());
trans.set_response_status(tlm::TLM_OK_RESPONSE);
auto hm_entry = host_mem_lut.getEntry(adr);
if(cmd == tlm::TLM_READ_COMMAND) {
Expand Down Expand Up @@ -291,26 +287,45 @@ int memory<SIZE, BUSWIDTH, PAGE_ADDR_BITS, USE_CYCLES>::handle_operation(tlm::tl
}
} else if(cmd == tlm::TLM_WRITE_COMMAND) {
delay += delay_spec_type<USE_CYCLES>::get_effective_value(clk_period, wr_resp_delay);
if(hm_entry.ptr) {
if(UNLIKELY(hm_entry.ptr)) {
auto hm_start_offs = adr - hm_entry.base;
auto hm_end_offs = adr + len - hm_entry.base;
auto hm_ptr = hm_entry.ptr + hm_start_offs;
auto transfer_length = hm_end_offs < hm_entry.size ? len : hm_end_offs - hm_start_offs;
std::copy(ptr, ptr + transfer_length, hm_ptr);
if(scattered) {
for(size_t i = 0; i < transfer_length; ++i)
if(byt[i] == 0xff)
*(hm_ptr + i) = *(ptr + i);
} else
std::copy(ptr, ptr + transfer_length, hm_ptr);
} else {
auto& p = mem(adr / mem.page_size);
auto offs = adr & mem.page_addr_mask;
if((offs + len) > mem.page_size) {
if(UNLIKELY((offs + len) > mem.page_size)) { // we cross a page of the memory
auto first_part = mem.page_size - offs;
std::copy(ptr, ptr + first_part, p.data() + offs);
if(scattered) {
for(size_t i = 0; i < first_part; ++i)
if(byt[i] == 0xff)
*(p.data() + offs + i) = *(ptr + i);
} else
std::copy(ptr, ptr + first_part, p.data() + offs);
auto& p2 = mem((adr / mem.page_size) + 1);
std::copy(ptr + first_part, ptr + len, p2.data());
} else {
std::copy(ptr, ptr + len, p.data() + offs);
if(scattered) {
for(size_t i = 0, j = first_part; j < len; ++i, ++j)
if(byt[j] == 0xff)
*(p2.data() + i) = *(ptr + j);
} else
std::copy(ptr + first_part, ptr + len, p2.data());
} else { // we stay within a page of the memory
if(scattered) {
for(size_t i = 0; i < len; ++i)
if(byt[i] == 0xff)
*(p.data() + offs + i) = *(ptr + i);
} else
std::copy(ptr, ptr + len, p.data() + offs);
}
}
}
trans.set_dmi_allowed(allow_dmi.get_value());
return len;
}

Expand Down
37 changes: 37 additions & 0 deletions tests/memory_subsys/memory_test.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -67,6 +67,43 @@ TEST_CASE("dmi_access", "[memory][tlm-level]") {
sc_start(dut.clk.read());
}

TEST_CASE("scattered_access", "[memory][tlm-level]") {
auto& dut = factory::get<testbench>();

auto f = [&dut](uint64_t addr) {
sc_core::sc_time delay = sc_core::SC_ZERO_TIME;

tlm::tlm_generic_payload init;
prepare_trans(init, tlm::TLM_WRITE_COMMAND, addr, 16);
for(size_t i = 0; i < 16; ++i)
*(init.get_data_ptr() + i) = 0;
dut.mem3.handle_operation(init, delay);

std::array<uint8_t, 4> write_data{{0xAAu, 0xBBu, 0xCC, 0xDD}};
std::array<uint8_t, 4> be_data{{0xFFu, 0x00u, 0xFF, 0x00}};
tlm::tlm_generic_payload write;
prepare_trans(write, tlm::TLM_WRITE_COMMAND, addr, 4);
std::copy(write_data.begin(), write_data.end(), write.get_data_ptr());
write.set_byte_enable_length(be_data.size());
write.set_byte_enable_ptr(be_data.data());
dut.mem3.handle_operation(write, delay);

std::array<uint8_t, 4> read_buf{{0xEEu, 0x00u, 0x00u, 0xEEu}};
tlm::tlm_generic_payload read;
prepare_trans(read, tlm::TLM_READ_COMMAND, addr, 4);
dut.mem3.handle_operation(read, delay);
std::copy(read.get_data_ptr(), read.get_data_ptr() + read.get_data_length(), read_buf.begin());

REQUIRE(read_buf[0] == write_data[0]);
REQUIRE(read_buf[1] == 0x00u);
REQUIRE(read_buf[2] == write_data[2]);
REQUIRE(read_buf[3] == 0x00u);
};
f(0x100);
constexpr uint64_t kPageSize = dut.mem3.getPageSize();
f(kPageSize - 2);
}

TEST_CASE("page_boundary_check", "[memory][tlm-level]") {
auto& dut = factory::get<testbench>();
constexpr uint64_t kPageSize = dut.mem3.getPageSize();
Expand Down
Loading