Fixed IMASK access in DSP & GPU, more CPU browser refinements.

[virtualjaguar] / src / gpu.cpp

diff --git a/src/gpu.cpp b/src/gpu.cpp
index e1fdd41e8751be298c26804e4a198a37de0c4f7d..c57b948d5088751dd169e4d20f0d5e89a7a11a3c 100644 (file)
--- a/src/gpu.cpp
+++ b/src/gpu.cpp
@@ -647,12 +647,15 @@ void GPUWriteWord(uint32 offset, uint16 data, uint32 who/*=UNKNOWN*/)
                {
 //WriteLog("[GPU W16:%08X,%04X]", offset, data);
                        uint32 old_data = GPUReadLong(offset & 0xFFFFFFC, who);
+
                        if (offset & 0x02)
                                old_data = (old_data & 0xFFFF0000) | (data & 0xFFFF);
                        else
                                old_data = (old_data & 0x0000FFFF) | ((data & 0xFFFF) << 16);
+
                        GPUWriteLong(offset & 0xFFFFFFC, old_data, who);
                }
+
                return;
        }
        else if ((offset == GPU_WORK_RAM_BASE + 0x0FFF) || (GPU_CONTROL_RAM_BASE + 0x1F))
@@ -700,7 +703,9 @@ void GPUWriteLong(uint32 offset, uint32 data, uint32 who/*=UNKNOWN*/)
                case 0x00:
                {
                        bool IMASKCleared = (gpu_flags & IMASK) && !(data & IMASK);
-                       gpu_flags = data;
+                       // NOTE: According to the JTRM, writing a 1 to IMASK has no effect; only the
+                       //       IRQ logic can set it. So we mask it out here to prevent problems...
+                       gpu_flags = data & (~IMASK);
                        gpu_flag_z = gpu_flags & ZERO_FLAG;
                        gpu_flag_c = (gpu_flags & CARRY_FLAG) >> 1;
                        gpu_flag_n = (gpu_flags & NEGA_FLAG) >> 2;