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pc_vga: vsync interrupt support

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This commit is contained in:
Dirk Best 2025-01-05 20:01:27 +01:00
parent a672b823a8
commit 97ca3db148
2 changed files with 28 additions and 6 deletions
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30
src/devices/video/pc_vga.cpp
View File

@ -60,7 +60,7 @@
#define LOG_DSW (1U << 3) // Input sense at $3c2
#define LOG_CRTC (1U << 4) // CRTC setups with monitor geometry
#define VERBOSE (LOG_GENERAL | LOG_WARN | LOG_DSW)
#define VERBOSE (LOG_GENERAL | LOG_WARN)
//#define LOG_OUTPUT_FUNC osd_printf_info
#include "logmacro.h"
@ -117,6 +117,7 @@ vga_device::vga_device(const machine_config &mconfig, device_type type, const ch
, device_memory_interface(mconfig, *this)
, vga(*this)
, m_input_sense(*this, "VGA_SENSE")
, m_vsync_cb(*this)
{
m_main_if_space_config = address_space_config("io_regs", ENDIANNESS_LITTLE, 8, 4, 0, address_map_constructor(FUNC(vga_device::io_3bx_3dx_map), this));
m_crtc_space_config = address_space_config("crtc_regs", ENDIANNESS_LITTLE, 8, 8, 0, address_map_constructor(FUNC(vga_device::crtc_map), this));
@ -223,6 +224,7 @@ void vga_device::device_start()
save_item(NAME(vga.crtc.map13));
save_item(NAME(vga.crtc.irq_clear));
save_item(NAME(vga.crtc.irq_disable));
save_item(NAME(vga.crtc.irq_latch));
save_item(NAME(vga.crtc.no_wrap));
save_item(NAME(vga.gc.index));
@ -498,6 +500,7 @@ u8 vga_device::input_status_0_r(offs_t offset)
LOGDSW("Reading sense bit %d\n", sense_bit);
if(BIT(m_input_sense->read(), sense_bit))
res |= 0x10;
res |= vga.crtc.irq_latch << 7;
return res;
}
@ -905,12 +908,20 @@ void vga_device::crtc_map(address_map &map)
return res;
}),
NAME([this](offs_t offset, u8 data) {
vga.crtc.protect_enable = (data & 0x80) >> 7;
vga.crtc.bandwidth = (data & 0x40) >> 6;
vga.crtc.protect_enable = BIT(data, 7);
vga.crtc.bandwidth = BIT(data, 6);
// IRQ: Original VGA only supports this for PS/2, but clone cards may supports this on ISA too
// see https://scalibq.wordpress.com/2022/12/06/the-myth-of-the-vertical-retrace-interrupt/
vga.crtc.irq_disable = BIT(data, 5);
vga.crtc.irq_clear = BIT(data, 4);
vga.crtc.vert_retrace_end = (vga.crtc.vert_retrace_end & ~0xf) | (data & 0x0f);
// TODO: these two doesn't seem part of the spec
vga.crtc.irq_clear = (data & 0x10) >> 4;
vga.crtc.irq_disable = (data & 0x20) >> 5;
if (vga.crtc.irq_clear == 0)
{
vga.crtc.irq_latch = 0;
m_vsync_cb(0);
}
LOGCRTC("CR11 V retrace end %02x -> %02d protect enable %d bandwidth %d irq %02x\n"
, data
, vga.crtc.vert_retrace_end
@ -1839,6 +1850,13 @@ TIMER_CALLBACK_MEMBER(vga_device::vblank_timer_cb)
{
vga.crtc.start_addr = latch_start_addr();
vga.attribute.pel_shift = vga.attribute.pel_shift_latch;
if (vga.crtc.irq_latch == 0 && vga.crtc.irq_disable == 0)
{
vga.crtc.irq_latch = 1;
m_vsync_cb(1);
}
m_vblank_timer->adjust( screen().time_until_pos(vga.crtc.vert_blank_start + vga.crtc.vert_blank_end) );
}

4
src/devices/video/pc_vga.h
View File

@ -48,6 +48,7 @@ public:
void set_offset(uint16_t val) { vga.crtc.offset = val; }
void set_vram_size(size_t vram_size) { vga.svga_intf.vram_size = vram_size; }
auto vsync_cb() { return m_vsync_cb.bind(); }
// FIXME: should be protected, but virge_pci.cpp violates this
inline uint16_t get_crtc_port() { return BIT(vga.miscellaneous_output, 0) ? 0x3d0 : 0x3b0; }
@ -235,6 +236,7 @@ protected:
/**/ uint8_t map13;
/**/ uint8_t irq_clear;
/**/ uint8_t irq_disable;
uint8_t irq_latch;
uint8_t no_wrap;
} crtc;
@ -305,6 +307,8 @@ protected:
address_space_config m_atc_space_config;
bool m_ioas = false;
devcb_write_line m_vsync_cb;
private:
uint32_t start_addr();
};