diff options
Diffstat (limited to 'src/devices/machine/spg2xx_sysdma.cpp')
-rw-r--r-- | src/devices/machine/spg2xx_sysdma.cpp | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/src/devices/machine/spg2xx_sysdma.cpp b/src/devices/machine/spg2xx_sysdma.cpp new file mode 100644 index 00000000000..fe0d61ea395 --- /dev/null +++ b/src/devices/machine/spg2xx_sysdma.cpp @@ -0,0 +1,117 @@ +// license:BSD-3-Clause +// copyright-holders:Ryan Holtz +/***************************************************************************** + + SunPlus SPG2xx-series SoC peripheral emulation (System DMA) + +**********************************************************************/ + +#include "emu.h" +#include "spg2xx_sysdma.h" + +DEFINE_DEVICE_TYPE(SPG2XX_SYSDMA, spg2xx_sysdma_device, "spg2xx_sysdma", "SPG240-series System-on-a-Chip System DMA") + +#define LOG_DMA (1U << 9) +#define LOG_ALL (LOG_DMA) + +#define VERBOSE (0) +#include "logmacro.h" + + + +spg2xx_sysdma_device::spg2xx_sysdma_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) + : device_t(mconfig, SPG2XX_SYSDMA, tag, owner, clock) + , m_cpu(*this, finder_base::DUMMY_TAG) +{ +} + +void spg2xx_sysdma_device::device_start() +{ + save_item(NAME(m_dma_regs)); +} + +void spg2xx_sysdma_device::device_reset() +{ + memset(m_dma_regs, 0, 0x4 * sizeof(uint16_t)); +} + +/************************* +* Machine Hardware * +*************************/ + +READ16_MEMBER(spg2xx_sysdma_device::dma_r) +{ + offset &= 0x3; + + uint16_t val = m_dma_regs[offset]; + switch (offset) + { + + case 0x000: // DMA Source (L) + LOGMASKED(LOG_DMA, "dma_r: DMA Source (lo) = %04x\n", val); + break; + + case 0x001: // DMA Source (H) + LOGMASKED(LOG_DMA, "dma_r: DMA Source (hi) = %04x\n", val); + break; + + case 0x002: // DMA Length + LOGMASKED(LOG_DMA, "dma_r: DMA Length = %04x\n", 0); + val = 0; + break; + + case 0x003: // DMA Destination + LOGMASKED(LOG_DMA, "dma_r: DMA Dest = %04x\n", val); + break; + } + + return val; +} + +WRITE16_MEMBER(spg2xx_sysdma_device::dma_w) +{ + offset &= 0x3; + + switch (offset) + { + case 0x000: // DMA Source (lo) + LOGMASKED(LOG_DMA, "dma_w: DMA Source (lo) = %04x\n", data); + m_dma_regs[offset] = data; + break; + + case 0x001: // DMA Source (hi) + LOGMASKED(LOG_DMA, "dma_w: DMA Source (hi) = %04x\n", data); + m_dma_regs[offset] = data; + break; + + case 0x002: // DMA Length + LOGMASKED(LOG_DMA, "dma_w: DMA Length = %04x\n", data); + if (!(data & 0xc000)) // jak_dora writes 0xffff here which ends up trashing registers etc. why? such writes can't be valid + do_cpu_dma(data); + break; + + case 0x003: // DMA Destination + LOGMASKED(LOG_DMA, "dma_w: DMA Dest = %04x\n", data); + m_dma_regs[offset] = data; + break; + } +} + +void spg2xx_sysdma_device::do_cpu_dma(uint32_t len) +{ + address_space &mem = m_cpu->space(AS_PROGRAM); + + uint32_t src = ((m_dma_regs[0x001] & 0x3f) << 16) | m_dma_regs[0x000]; + uint32_t dst = m_dma_regs[0x003] & 0x3fff; + + for (uint32_t j = 0; j < len; j++) + { + mem.write_word((dst + j) & 0x3fff, mem.read_word(src + j)); + } + + src += len; + m_dma_regs[0x000] = (uint16_t)src; + m_dma_regs[0x001] = (src >> 16) & 0x3f; + m_dma_regs[0x002] = 0; + m_dma_regs[0x003] = (dst + len) & 0x3fff; +} |