diff --git a/core/libs/prx/libSceAgc/CMakeLists.txt b/core/libs/prx/libSceAgc/CMakeLists.txt
index dec965a2f..1db3169a0 100644
--- a/core/libs/prx/libSceAgc/CMakeLists.txt
+++ b/core/libs/prx/libSceAgc/CMakeLists.txt
@@ -68,3 +68,21 @@ target_include_directories(agc_command_tests PRIVATE ${LIBS_INCLUDE_DIR})
 target_link_libraries(agc_command_tests PRIVATE libSceAgc libc)
 configure_windows_unwind(agc_command_tests)
 configure_windows_unwind(libSceAgc)
+
+add_executable(agc_register_command_tests EXCLUDE_FROM_ALL
+        tests/RegisterCommands.cpp
+        Command/src/Packet.cpp
+        DcbState/src/Registers.cpp
+        Patch/src/IndirectRegisters.cpp
+)
+target_include_directories(agc_register_command_tests PRIVATE ${LIBS_INCLUDE_DIR})
+target_link_libraries(agc_register_command_tests PRIVATE libc)
+configure_windows_unwind(agc_register_command_tests)
+if(BUILD_TESTING)
+    set_target_properties(agc_register_command_tests PROPERTIES EXCLUDE_FROM_ALL FALSE)
+    add_test(NAME agc_register_command_tests COMMAND agc_register_command_tests)
+    if(WIN32)
+        set_tests_properties(agc_register_command_tests PROPERTIES ENVIRONMENT_MODIFICATION
+            "PATH=path_list_prepend:$<TARGET_FILE_DIR:libc>")
+    endif()
+endif()
diff --git a/core/libs/prx/libSceAgc/Command/include/Packet.hpp b/core/libs/prx/libSceAgc/Command/include/Packet.hpp
index f95361fd9..7b92007d8 100644
--- a/core/libs/prx/libSceAgc/Command/include/Packet.hpp
+++ b/core/libs/prx/libSceAgc/Command/include/Packet.hpp
@@ -21,6 +21,7 @@ std::uint32_t* WriteRegisters(CommandBuffer* buffer, std::uint32_t opcode, const
 std::uint32_t* WriteIndirectRegisters(CommandBuffer* buffer, std::uint32_t opcode, const volatile ShaderRegister* registers, std::uint32_t count, const char* function);
 void PatchIndirectAddress(std::uint32_t* packet, std::uint32_t opcode, const volatile ShaderRegister* registers, const char* function);
 void PatchIndirectCount(std::uint32_t* packet, std::uint32_t opcode, std::uint32_t count, const char* function);
+void SetIndirectCount(std::uint32_t* packet, std::uint32_t opcode, std::uint32_t count, const char* function);
 
 }
 
diff --git a/core/libs/prx/libSceAgc/Command/src/Packet.cpp b/core/libs/prx/libSceAgc/Command/src/Packet.cpp
index b32303b1c..62a12734b 100644
--- a/core/libs/prx/libSceAgc/Command/src/Packet.cpp
+++ b/core/libs/prx/libSceAgc/Command/src/Packet.cpp
@@ -159,4 +159,11 @@ void PatchIndirectCount(std::uint32_t* packet, std::uint32_t opcode, std::uint32
     packet[4] += count;
 }
 
+void SetIndirectCount(std::uint32_t* packet, std::uint32_t opcode, std::uint32_t count, const char* function) {
+    ValidatePacket(packet, opcode, 5, function);
+    Require(packet[3] == 0x80000000u && packet[4] <= 0x3fffu, function, "invalid indirect register packet");
+    CheckBits(count, 0x3fffu, function);
+    packet[4] = count;
+}
+
 }
diff --git a/core/libs/prx/libSceAgc/DcbState/src/Registers.cpp b/core/libs/prx/libSceAgc/DcbState/src/Registers.cpp
index 36c25d7f5..11d3ce528 100644
--- a/core/libs/prx/libSceAgc/DcbState/src/Registers.cpp
+++ b/core/libs/prx/libSceAgc/DcbState/src/Registers.cpp
@@ -21,9 +21,8 @@ std::uint32_t* APS5_VABI sceAgcDcbSetCxRegistersIndirect(CommandBuffer* buf, con
 }
 
 std::uint32_t APS5_VABI sceAgcDcbSetCxRegistersIndirectGetSize(std::uint32_t numRegs) {
-    (void)numRegs;
-    NotImplemented_nid_no_patch(__func__);
-    return 0;
+    Agc::Command::CheckBits(numRegs, 0x3fffu, __func__);
+    return 20;
 }
 
 uint32_t* APS5_VABI sceAgcDcbSetShRegisterDirect(CommandBuffer* buf, ShaderRegister reg) {
@@ -56,9 +55,8 @@ std::uint32_t* APS5_VABI sceAgcDcbSetUcRegistersIndirect(CommandBuffer* buf, con
 }
 
 std::uint32_t APS5_VABI sceAgcDcbSetUcRegistersIndirectGetSize(std::uint32_t numRegs) {
-    (void)numRegs;
-    NotImplemented_nid_no_patch(__func__);
-    return 0;
+    Agc::Command::CheckBits(numRegs, 0x3fffu, __func__);
+    return 20;
 }
 
 }
diff --git a/core/libs/prx/libSceAgc/Patch/src/IndirectRegisters.cpp b/core/libs/prx/libSceAgc/Patch/src/IndirectRegisters.cpp
index f14d7b320..ff90be0cd 100644
--- a/core/libs/prx/libSceAgc/Patch/src/IndirectRegisters.cpp
+++ b/core/libs/prx/libSceAgc/Patch/src/IndirectRegisters.cpp
@@ -19,11 +19,9 @@ int APS5_VABI sceAgcSetCxRegIndirectPatchSetAddress(std::uint32_t* cmd, const vo
     return 0;
 }
 
-int APS5_VABI sceAgcSetCxRegIndirectPatchSetNumRegisters(uint32_t* cmd, uint32_t num_regs) {
- (void)cmd;
- (void)num_regs;
- NotImplemented_nid_no_patch(__func__);
- return 0;
+int APS5_VABI sceAgcSetCxRegIndirectPatchSetNumRegisters(std::uint32_t* cmd, std::uint32_t numRegs) {
+    Agc::Command::SetIndirectCount(cmd, 0x9fu, numRegs, __func__);
+    return 0;
 }
 
 int APS5_VABI sceAgcSetShRegIndirectPatchAddRegisters(std::uint32_t* cmd, std::uint32_t numRegs) {
@@ -36,11 +34,9 @@ int APS5_VABI sceAgcSetShRegIndirectPatchSetAddress(std::uint32_t* cmd, const vo
     return 0;
 }
 
-int APS5_VABI sceAgcSetShRegIndirectPatchSetNumRegisters(uint32_t* cmd, uint32_t num_regs) {
- (void)cmd;
- (void)num_regs;
- NotImplemented_nid_no_patch(__func__);
- return 0;
+int APS5_VABI sceAgcSetShRegIndirectPatchSetNumRegisters(std::uint32_t* cmd, std::uint32_t numRegs) {
+    Agc::Command::SetIndirectCount(cmd, 0x63u, numRegs, __func__);
+    return 0;
 }
 
 int APS5_VABI sceAgcSetUcRegIndirectPatchAddRegisters(std::uint32_t* cmd, std::uint32_t numRegs) {
@@ -53,11 +49,9 @@ int APS5_VABI sceAgcSetUcRegIndirectPatchSetAddress(std::uint32_t* cmd, const vo
     return 0;
 }
 
-int APS5_VABI sceAgcSetUcRegIndirectPatchSetNumRegisters(uint32_t* cmd, uint32_t num_regs) {
- (void)cmd;
- (void)num_regs;
- NotImplemented_nid_no_patch(__func__);
- return 0;
+int APS5_VABI sceAgcSetUcRegIndirectPatchSetNumRegisters(std::uint32_t* cmd, std::uint32_t numRegs) {
+    Agc::Command::SetIndirectCount(cmd, 0x64u, numRegs, __func__);
+    return 0;
 }
 
 }
diff --git a/core/libs/prx/libSceAgc/tests/RegisterCommands.cpp b/core/libs/prx/libSceAgc/tests/RegisterCommands.cpp
new file mode 100644
index 000000000..e40249ef6
--- /dev/null
+++ b/core/libs/prx/libSceAgc/tests/RegisterCommands.cpp
@@ -0,0 +1,116 @@
+#include "prx/libSceAgc/Command/include/Packet.hpp"
+
+#include <algorithm>
+#include <array>
+#include <cstdio>
+#include <stdexcept>
+
+extern "C" {
+std::uint32_t* APS5_VABI sceAgcDcbSetCxRegisterDirect(CommandBuffer*, ShaderRegister);
+std::uint32_t* APS5_VABI sceAgcDcbSetShRegisterDirect(CommandBuffer*, ShaderRegister);
+std::uint32_t* APS5_VABI sceAgcDcbSetUcRegisterDirect(CommandBuffer*, ShaderRegister);
+std::uint32_t APS5_VABI sceAgcDcbSetCxRegisterDirectGetSize();
+std::uint32_t APS5_VABI sceAgcDcbSetShRegisterDirectGetSize();
+std::uint32_t APS5_VABI sceAgcDcbSetUcRegisterDirectGetSize();
+std::uint32_t* APS5_VABI sceAgcDcbSetCxRegistersIndirect(CommandBuffer*, const volatile ShaderRegister*, std::uint32_t);
+std::uint32_t* APS5_VABI sceAgcDcbSetShRegistersIndirect(CommandBuffer*, const volatile ShaderRegister*, std::uint32_t);
+std::uint32_t* APS5_VABI sceAgcDcbSetUcRegistersIndirect(CommandBuffer*, const volatile ShaderRegister*, std::uint32_t);
+std::uint32_t APS5_VABI sceAgcDcbSetCxRegistersIndirectGetSize(std::uint32_t);
+std::uint32_t APS5_VABI sceAgcDcbSetShRegistersIndirectGetSize(std::uint32_t);
+std::uint32_t APS5_VABI sceAgcDcbSetUcRegistersIndirectGetSize(std::uint32_t);
+int APS5_VABI sceAgcSetCxRegIndirectPatchSetNumRegisters(std::uint32_t*, std::uint32_t);
+int APS5_VABI sceAgcSetShRegIndirectPatchSetNumRegisters(std::uint32_t*, std::uint32_t);
+int APS5_VABI sceAgcSetUcRegIndirectPatchSetNumRegisters(std::uint32_t*, std::uint32_t);
+}
+
+namespace {
+
+void check(bool condition, const char* message) {
+    if (!condition) throw std::runtime_error(message);
+}
+
+template <typename TAction>
+void expectFailure(TAction action) {
+    try {
+        action();
+    } catch (const std::runtime_error&) {
+        return;
+    }
+    throw std::runtime_error("expected invalid input to fail");
+}
+
+struct Storage {
+    std::array<std::uint32_t, 16> words{};
+    CommandBuffer buffer{words.data(), words.data() + words.size(), words.data(), words.data() + words.size(), nullptr, nullptr, 0};
+};
+
+void testDirect() {
+    const std::array writers{sceAgcDcbSetCxRegisterDirect, sceAgcDcbSetShRegisterDirect, sceAgcDcbSetUcRegisterDirect};
+    const std::array sizes{sceAgcDcbSetCxRegisterDirectGetSize, sceAgcDcbSetShRegisterDirectGetSize, sceAgcDcbSetUcRegisterDirectGetSize};
+    const std::array headers{0xc0016900u, 0xc0017600u, 0xc0017900u};
+    for (std::size_t i = 0; i < writers.size(); ++i) {
+        Storage storage;
+        storage.words.fill(0xabcdef01u);
+        auto* packet = writers[i](&storage.buffer, {0xffffu, 0x12345678u});
+        const std::array expected{headers[i], 0xffffu, 0x12345678u};
+        check(packet == storage.words.data() && std::equal(expected.begin(), expected.end(), packet), "incorrect direct register packet");
+        check(storage.buffer.cursor_up == packet + 3 && sizes[i]() == 12, "direct size/cursor mismatch");
+        check(packet[3] == 0xabcdef01u, "direct command overwrote following word");
+        const auto before = storage.words;
+        expectFailure([&] { writers[i](&storage.buffer, {0x10000u, 1}); });
+        expectFailure([&] { writers[i](nullptr, {0, 1}); });
+        storage.buffer.cursor_down = storage.buffer.cursor_up + 2;
+        expectFailure([&] { writers[i](&storage.buffer, {0, 1}); });
+        check(storage.words == before && storage.buffer.cursor_up == packet + 3, "invalid direct write modified buffer");
+    }
+}
+
+void testIndirect() {
+    const std::array writers{sceAgcDcbSetCxRegistersIndirect, sceAgcDcbSetShRegistersIndirect, sceAgcDcbSetUcRegistersIndirect};
+    const std::array sizes{sceAgcDcbSetCxRegistersIndirectGetSize, sceAgcDcbSetShRegistersIndirectGetSize, sceAgcDcbSetUcRegistersIndirectGetSize};
+    const std::array setters{sceAgcSetCxRegIndirectPatchSetNumRegisters, sceAgcSetShRegIndirectPatchSetNumRegisters, sceAgcSetUcRegIndirectPatchSetNumRegisters};
+    const std::array headers{0xc0039f00u, 0xc0036300u, 0xc0036400u};
+    ShaderRegister reg{0x10u, 7};
+    for (std::size_t i = 0; i < writers.size(); ++i) {
+        Storage storage;
+        auto* packet = writers[i](&storage.buffer, &reg, 1);
+        const auto original = storage.words;
+        check(packet[0] == headers[i] && storage.buffer.cursor_up == packet + 5, "incorrect indirect packet");
+        for (const auto count : {0u, 0x3fffu, 2u}) {
+            check(sizes[i](count) == 20, "indirect size mismatch");
+            check(setters[i](packet, count) == 0 && packet[4] == count, "indirect count was not replaced");
+            auto expected = original;
+            expected[4] = count;
+            check(storage.words == expected, "count setter modified unrelated packet data");
+        }
+        const auto before = storage.words;
+        for (const auto count : {0x4000u, 0xffffffffu}) {
+            expectFailure([&] { sizes[i](count); });
+            expectFailure([&] { setters[i](packet, count); });
+        }
+        expectFailure([&] { setters[i](nullptr, 0); });
+        expectFailure([&] { setters[(i + 1) % setters.size()](packet, 0); });
+        check(storage.words == before, "invalid count setter modified packet");
+        for (const auto field : {0u, 3u, 4u}) {
+            storage.words = before;
+            packet[field] = field == 0 ? headers[i] ^ 0x10000u : 0xffffffffu;
+            const auto malformed = storage.words;
+            expectFailure([&] { setters[i](packet, 1); });
+            check(storage.words == malformed, "setter modified malformed packet");
+        }
+    }
+}
+
+}
+
+int main() {
+    try {
+        testDirect();
+        testIndirect();
+        std::puts("AGC register command tests passed");
+        return 0;
+    } catch (const std::exception& error) {
+        std::fprintf(stderr, "%s\n", error.what());
+        return 1;
+    }
+}