Palacios Public Git Repository

To checkout Palacios execute

  git clone http://v3vee.org/palacios/palacios.web/palacios.git
This will give you the master branch. You probably want the devel branch or one of the release branches. To switch to the devel branch, simply execute
  cd palacios
  git checkout --track -b devel origin/devel
The other branches are similar.


Updated NE2000 and RTL8139 to conform to interface changes
[palacios.git] / palacios / src / devices / vga.c
index b7b0a36..6e5687c 100644 (file)
 #include <palacios/vmm_types.h>
 #include <palacios/vm_guest_mem.h>
 #include <palacios/vmm_io.h>
-#include <palacios/vmm_graphics_console.h>
+#include <interfaces/vmm_graphics_console.h>
 
 #include "vga_regs.h"
 
+#ifndef V3_CONFIG_DEBUG_VGA
+#undef PrintDebug
+#define PrintDebug(fmt, args...)
+#endif
+
+#define DEBUG_MEM_DATA    0
+#define DEBUG_DEEP_MEM    0
+#define DEBUG_DEEP_RENDER 0
+
+
 #define MEM_REGION_START 0xa0000
 #define MEM_REGION_END   0xc0000
 #define MEM_REGION_NUM_PAGES (((MEM_REGION_END)-(MEM_REGION_START))/4096)
@@ -82,6 +92,10 @@ typedef uint8_t *vga_map; // points to MAP_SIZE data
 
 #define VGA_DAC_NUM_ENTRIES 256
 
+
+#define VGA_FONT_WIDTH      8
+#define VGA_MAX_FONT_HEIGHT 32
+
 struct vga_misc_regs {
     /* Read: 0x3cc; Write: 0x3c2 */
     struct vga_misc_out_reg        vga_misc_out;
@@ -148,7 +162,7 @@ struct vga_crt_controller_regs {
     /* index 8 */
     struct vga_preset_row_scan_reg vga_preset_row_scan;
     /* index 9 */
-    struct vga_max_row_scan_reg vga_row_scan;
+    struct vga_max_row_scan_reg vga_max_row_scan;
     /* index 10 */
     struct vga_cursor_start_reg vga_cursor_start;
     /* index 11 */
@@ -166,7 +180,7 @@ struct vga_crt_controller_regs {
     /* index 17 */
     struct vga_vertical_retrace_end_reg vga_vertical_retrace_end;
     /* index 18 */
-    vga_vertical_display_enable_end_reg vga_vertical_display_enable;
+    vga_vertical_display_enable_end_reg vga_vertical_display_enable_end;
     /* index 19 */
     vga_offset_reg vga_offset;
     /* index 20 */
@@ -268,7 +282,7 @@ struct vga_dac_regs {
     
 
 struct vga_internal {
-    struct vm_device *dev;  
+    struct vm_device *dev; 
     
     bool passthrough;
     bool skip_next_passthrough_out; // for word access 
@@ -316,52 +330,707 @@ struct vga_internal {
 };
 
 
+typedef enum {PLANAR_SHIFT, PACKED_SHIFT, C256_SHIFT} shift_mode_t;
 
-static int render(struct vga_internal *vga)
+
+static void find_text_char_dim(struct vga_internal *vga, uint32_t *w, uint32_t *h)
 {
-    vga->updates_since_render++;
+    *w = (vga->vga_sequencer.vga_clocking_mode.dot8 ? 8 : 9);
 
-    if (vga->host_cons && v3_graphics_console_inform_update(vga->host_cons)>0) { 
-       // Draw some crap for testing for now
+    *h = vga->vga_crt_controller.vga_max_row_scan.max_scan_line+1;
 
-       void *fb;
-       struct v3_frame_buffer_spec *s;
+}
 
-       fb = v3_graphics_console_get_frame_buffer_data_rw(vga->host_cons,&(vga->target_spec));
+static void find_text_res(struct vga_internal *vga, uint32_t *width, uint32_t *height)
+{
+    uint32_t vert_lsb, vert_msb;
+    uint32_t ph;
+    uint32_t ch, cw;
+
+    *width = (vga->vga_crt_controller.vga_horizontal_display_enable_end + 1) 
+       - vga->vga_crt_controller.vga_end_horizontal_blanking.display_enable_skew;
+
+    vert_lsb = vga->vga_crt_controller.vga_vertical_display_enable_end; // 8 bits here
+    vert_msb = (vga->vga_crt_controller.vga_overflow.vertical_disp_enable_end9 << 1)  // 2 bits here
+       + (vga->vga_crt_controller.vga_overflow.vertical_disp_enable_end8);
+              
+    ph  = ( (vert_msb << 8) + vert_lsb + 1) ; // pixels high (scanlines)
+
+    find_text_char_dim(vga,&cw, &ch);
+
+    *height = ph / ch; 
+
+}
+
+
+static void find_text_data_start(struct vga_internal *vga, void **data)
+{
+    uint32_t offset;
+
+    offset = vga->vga_crt_controller.vga_start_address_high;
+    offset <<= 8;
+    offset += vga->vga_crt_controller.vga_start_address_low;
+
+    *data = vga->map[0]+offset;
+
+}
+
+
+static void find_text_attr_start(struct vga_internal *vga, void **data)
+{
+    uint32_t offset;
+
+    offset = vga->vga_crt_controller.vga_start_address_high;
+    offset <<= 8;
+    offset += vga->vga_crt_controller.vga_start_address_low;
+
+    *data = vga->map[1]+offset;
+
+}
+
+static void find_text_cursor_pos(struct vga_internal *vga, uint32_t *x, uint32_t *y, void **data)
+{
+    uint32_t w,h;
+    uint32_t offset;
+    uint32_t charsin;
+    void *buf;
+
+    find_text_res(vga,&w,&h);
+
+    find_text_data_start(vga,&buf);
+
+    offset = vga->vga_crt_controller.vga_cursor_location_high;
+    offset <<= 8;
+    offset += vga->vga_crt_controller.vga_cursor_location_low;
+
+    *data = vga->map[0]+offset;
+
+    charsin = (uint32_t)(*data - buf);
+    
+    *x = charsin % w;
+    *y = charsin / w;
+        
+}
+
+
+static void find_text_font_start(struct vga_internal *vga, void **data, uint8_t char_map)
+{
+    uint32_t mapa_offset, mapb_offset;
+
+
+    switch (char_map) { 
+       case 0:
+           mapa_offset = (vga->vga_sequencer.vga_char_map_select.char_map_a_sel_lsb << 1)
+                          + vga->vga_sequencer.vga_char_map_select.char_map_a_sel_msb ;
+           *data = vga->map[2] + mapa_offset;
+           break;
+           
+       case 1:
+           mapb_offset = (vga->vga_sequencer.vga_char_map_select.char_map_b_sel_lsb << 1)
+                          + vga->vga_sequencer.vga_char_map_select.char_map_b_sel_msb ;
+           *data = vga->map[2] + mapb_offset;
+           break;
+       default:
+           PrintError("vga: unknown char_map given to find_text_font_start\n");
+           break;
+           
+    }
+}
+
+static int extended_fontset(struct vga_internal *vga)
+{
+    if (vga->vga_sequencer.vga_mem_mode.extended_memory &&
+       ! ( (vga->vga_sequencer.vga_char_map_select.char_map_a_sel_lsb 
+            == vga->vga_sequencer.vga_char_map_select.char_map_b_sel_lsb) &&
+           (vga->vga_sequencer.vga_char_map_select.char_map_a_sel_msb 
+            == vga->vga_sequencer.vga_char_map_select.char_map_b_sel_msb))) { 
+       return 1;
+    } else {
+       return 0;
+    }
+
+}
+
+static int blinking(struct vga_internal *vga)
+{
+    return vga->vga_attribute_controller.vga_attribute_mode_control.enable_blink;
+}
+
+
+static void find_graphics_data_starting_offset(struct vga_internal *vga, uint32_t *offset)
+{
+
+    *offset = vga->vga_crt_controller.vga_start_address_high;
+    *offset <<= 8;
+    *offset += vga->vga_crt_controller.vga_start_address_low;
+}
+
+
+static void find_shift_mode(struct vga_internal *vga, shift_mode_t *mode)
+{
+    if (vga->vga_graphics_controller.vga_graphics_mode.c256) { 
+       *mode=C256_SHIFT;
+    } else {
+       if (vga->vga_graphics_controller.vga_graphics_mode.shift_reg_mode) {
+           *mode=PACKED_SHIFT;
+       } else {
+           *mode=PLANAR_SHIFT;
+       }
+    }
+}
+
+
+static void find_graphics_res(struct vga_internal *vga, uint32_t *width, uint32_t *height)
+{
+    uint32_t vert_lsb, vert_msb;
+
+    *width = ((vga->vga_crt_controller.vga_horizontal_display_enable_end + 1) 
+             - vga->vga_crt_controller.vga_end_horizontal_blanking.display_enable_skew);
+
+    *width *= (vga->vga_sequencer.vga_clocking_mode.dot8 ? 8 : 9);
+
+    vert_lsb = vga->vga_crt_controller.vga_vertical_display_enable_end; // 8 bits here
+    vert_msb = (vga->vga_crt_controller.vga_overflow.vertical_disp_enable_end9 << 1)  // 2 bits here
+       + (vga->vga_crt_controller.vga_overflow.vertical_disp_enable_end8);
+              
+    *height  = ( (vert_msb << 8) + vert_lsb + 1) ; // pixels high (scanlines)
+
+    // At this point we have the resolution in dot clocks across and scanlines top-to-bottom
+    // This is usually the resolution in pixels, but it can be monkeyed with
+    // at least in the following ways
+
+    // vga sequencer dot clock divide by two 
+    if (vga->vga_sequencer.vga_clocking_mode.dot_clock) { 
+       *width/=2;
+       *height/=2;
+    }
+
+    // crt_controller.max_row_scan.double_scan => each row twice for 200=>400
+    if (vga->vga_crt_controller.vga_max_row_scan.double_scan) { 
+       *height/=2;
+    }
+    
+    // crt_controller.crt_mode_control.count_by_two => pixels twice as wide as normal
+    if (vga->vga_crt_controller.vga_crt_mode_control.count_by_two) { 
+       *width /= 2;
+    }
+
+    // crt_controller.crt_mode_control.horizontal_retrace_select => pixels twice as tall as normal
+    if (vga->vga_crt_controller.vga_crt_mode_control.horizontal_retrace_select) { 
+       *height /= 2;
+    }
+    
+}
+
+
+static void find_graphics_cursor_pos(struct vga_internal *vga, uint32_t *x, uint32_t *y)
+{
+    // todo
+    *x=*y=0;
+}
+
+
+static void dac_lookup_24bit_color(struct vga_internal *vga,
+                                  uint8_t entry,
+                                  uint8_t *red,
+                                  uint8_t *green,
+                                  uint8_t *blue)
+{
+    // use internal or external palette?
+
+    vga_palette_reg *r = &(vga->vga_dac.vga_dac_palette[entry]);
+
+    // converting from 6 bits to 8 bits so << 2
+    *red = (*r & 0x3f) << 2;
+    *green = ((*r >> 8) & 0x3f) << 2;
+    *blue = ((*r >> 16) & 0x3f) << 2;
+
+}
+
+
+/*
+  Colors work like this:
+
+  4 bit modes:   index is to the internal palette on the attribute controller
+                 that supplies 6 bits, but we need 8 to index the dac
+                2 more (the msbs) are supplied from the color select register
+                 we can optionally overwrite bits 5 and 4 from the color
+                select register as well, depending on a selection bit
+                in the mode control register.   The result of all this is
+                8 bit index for the dac
+
+  8 bit modes:   the attribute controller passes the index straight through
+                 to the DAC.
+
+
+  The DAC translates from the 8 bit index into 6 bits per color channel
+  (18 bit color).   We mulitply by 4 to get 24 bit color.
+*/
+
+static void find_24bit_color(struct vga_internal *vga, 
+                            uint8_t val,
+                            uint8_t *red,
+                            uint8_t *green,
+                            uint8_t *blue)
+{
+    uint8_t di;  // ultimate dac index
+
+    if (vga->vga_attribute_controller.vga_attribute_mode_control.pixel_width) { 
+       // 8 bit mode does right to the DAC
+       di=val;
+    } else {
+       struct vga_internal_palette_reg pr = vga->vga_attribute_controller.vga_internal_palette[val%16];
+       di = pr.palette_data;
+       
+       // Fix bits 5-4 if needed
+       if (vga->vga_attribute_controller.vga_attribute_mode_control.p54_select) { 
+           di &= ~0x30;  // clear 5-4
+           di |= vga->vga_attribute_controller.vga_color_select.sc4 << 4;
+           di |= vga->vga_attribute_controller.vga_color_select.sc5 << 5;
+       }
+
+       // We must always produce bits 6 and 7
+       di &= ~0xc0; // clear 7-6
+       di |= vga->vga_attribute_controller.vga_color_select.sc6 << 6;
+       di |= vga->vga_attribute_controller.vga_color_select.sc7 << 7;
+    }
+       
+    dac_lookup_24bit_color(vga,di,red,green,blue);
+}
+       
+static void render_graphics(struct vga_internal *vga, void *fb)
+{
+
+    struct v3_frame_buffer_spec *spec = &(vga->target_spec);
+
+    uint32_t gw, gh; // graphics w/h
+    uint32_t fw, fh; // fb w/h
+    uint32_t rgw, rgh;  // region we can actually show on the frame buffer
+    
+
+    uint32_t fx, fy;     // pixel position within the frame buffer
+    
+    uint32_t offset;     // offset into the maps
+    uint8_t  m;        // map
+    uint8_t  p;          // pixel in the current map byte  (0..7)
+
+    uint8_t r,g,b;  // looked up colors for entry
+
+    void    *pixel;   // current pixel in the fb
+    uint8_t *red;     // and the channels in the pixel
+    uint8_t *green;   //
+    uint8_t *blue;    //
+
+    uint8_t db[4]; // 4 bytes read at a time
+    uint8_t pb[8]; // 8 pixels assembled at a time
+
+    shift_mode_t sm;   // shift mode
+
+    uint32_t cur_x, cur_y;
+    
+
+    find_graphics_res(vga,&gw,&gh);
+
+    find_shift_mode(vga,&sm);
+
+    find_graphics_cursor_pos(vga,&cur_x,&cur_y);
+
+    find_graphics_data_starting_offset(vga,&offset);
+
+    fw = spec->width;
+    fh = spec->height;
+
+
+    PrintDebug("vga: attempting graphics render (%s): graphics_res=(%u,%u), fb_res=(%u,%u), "
+               "fb=0x%p offset=0x%x\n",
+              sm == PLANAR_SHIFT ? "planar shift" : 
+              sm == PACKED_SHIFT ? "packed shift" : 
+              sm == C256_SHIFT ? "color256 shift" : "UNKNOWN",
+              gw,gh,fw,fh,fb,offset);
+
+    // First we need to clip to what we can actually show
+    rgw = gw < fw ? gw : fw;
+    rgh = gh < fh ? gh : fh;
+
+    if (gw%8) { 
+       PrintError("vga: warning: graphics width is not a multiple of 8\n");
+    }
+
+
+
+    // Now we scan across by row
+    for (fy=0;fy<gh;fy++) { 
+       // by column
+       for (fx=0;fx<gw;
+            fx += (sm==C256_SHIFT ? 4 : 8) , offset++ ) { 
+
+           // if any of these pixels are in the rendger region
+           if (fy < rgh && fx < rgw) {
+               // assemble all 4 or 8 pixels
+               
+               // fetch the data bytes
+               for (m=0;m<4;m++) { 
+                   db[m]=*((uint8_t*)(vga->map[m]+offset));
+               }
+                
+               // assemble
+               switch (sm) { 
+                   case PLANAR_SHIFT:
+                       for (p=0;p<8;p++) { 
+                           pb[p]= 
+                               (( db[0] >> 7) & 0x1) |
+                               (( db[1] >> 6) & 0x2) |
+                               (( db[2] >> 5) & 0x4) |
+                               (( db[3] >> 4) & 0x8) ;
+                           
+                           for (m=0;m<4;m++) { 
+                               db[m] <<= 1;
+                           }
+                       }
+                       break;
+                       
+                   case PACKED_SHIFT:
+                       // first 4 pixels use planes 0 and 2
+                       for (p=0;p<4;p++) { 
+                           pb[p] = 
+                               ((db[2] >> 4) & 0xc) |
+                               ((db[0] >> 6) & 0x3) ;
+                           db[2] <<= 2;
+                           db[0] <<= 2;
+                       }
+                       break;
+                       
+                       // next 4 pixels use planes 1 and 3
+                       for (p=4;p<8;p++) { 
+                           pb[p] = 
+                               ((db[3] >> 4) & 0xc) |
+                               ((db[1] >> 6) & 0x3) ;
+                           db[3] <<= 2;
+                           db[1] <<= 2;
+                       }
+                       break;
+
+                   case C256_SHIFT:
+                       // this one is either very bizarre or as simple as this
+                       for (p=0;p<4;p++) { 
+                           pb[p] = db[p];
+                       }
+                       break;
+               }
+
+               // draw each pixel
+               for (p=0;p< (sm==C256_SHIFT ? 4 : 8);p++) { 
+                   
+                   // find its color
+                   find_24bit_color(vga,pb[p],&r,&g,&b);
+               
+                   // find its position in the framebuffer;
+                   pixel =  fb + (((fx + p) + (fy*spec->width)) * spec->bytes_per_pixel);
+                   red = pixel + spec->red_offset;
+                   green = pixel + spec->green_offset;
+                   blue = pixel + spec->blue_offset;
+
+                   // draw it
+                   *red=r;
+                   *green=g;
+                   *blue=b;
+               }
+           }
+       }
+    }
+    
+    PrintDebug("vga: render done\n");
+}
+
+
+static void render_text_cursor(struct vga_internal *vga, void *fb)
+{
+}
+
+
+
+
+//
+// A variant of this function could render to
+// a text console interface as well
+//
+static void render_text(struct vga_internal *vga, void *fb)
+{
+    // line graphics enable bit means to  dupe column 8 to 9 when
+    // in 9 dot wide mode
+    // otherwise 9th dot is background
+
+    struct v3_frame_buffer_spec *spec = &(vga->target_spec);
+
+    uint32_t gw, gh; // graphics w/h
+    uint32_t tw, th; // text w/h
+    uint32_t rtw, rth; // rendered text w/h
+    uint32_t cw, ch; // char font w/h including 8/9
+    uint32_t fw, fh; // fb w/h
+
+    uint32_t px, py; // cursor position
+    
+    uint32_t x, y, l, p; // text location, line and pixel within the char
+    uint32_t fx, fy;     // pixel position within the frame buffer
+    
+    uint8_t *text_start; 
+    uint8_t *text;    // points to current char
+    uint8_t *attr;    // and its matching attribute
+    uint8_t *curs;    // to where the cursor is
+    uint8_t *font;    // to where the current font is
+
+    uint8_t fg_entry; // foreground color entry
+    uint8_t bg_entry; // background color entry
+    uint8_t fgr,fgg,fgb;    // looked up  foreground colors
+    uint8_t bgr,bgg,bgb;    // looked up  bg colors
+
+    uint8_t ct, ca;   // the current char and attribute
+    struct vga_attribute_byte a; // decoded attribute
+
+    void *pixel;      // current pixel in the fb
+    uint8_t *red;     // and the channels in the pixel
+    uint8_t *green;   //
+    uint8_t *blue;    //
+
+    
+
+    find_graphics_res(vga,&gw,&gh);
+    find_text_res(vga,&tw,&th);
+    find_text_char_dim(vga,&cw,&ch);
+    fw = spec->width;
+    fh = spec->height;
+
+    find_text_cursor_pos(vga,&px,&py,(void**)&curs);
+    find_text_data_start(vga,(void**)&text);
+    find_text_attr_start(vga,(void**)&attr);
+
+    find_text_font_start(vga,(void**)&font,0); // will need to switch this as we go since it is part of attr
 
-       s=&(vga->target_spec);
+    PrintDebug("vga: attempting text render: graphics_res=(%u,%u), fb_res=(%u,%u), text_res=(%u,%u), "
+              "char_res=(%u,%u), cursor=(%u,%u) font=0x%p, text=0x%p, attr=0x%p, curs=0x%p, fb=0x%p"
+              "graphics extension=%u, extended_fontset=%d, blinking=%d\n",
+              gw,gh,fw,fh,tw,th,cw,ch,px,py,font,text,attr,curs,fb,
+              vga->vga_attribute_controller.vga_attribute_mode_control.enable_line_graphics_char_code,
+              extended_fontset(vga), blinking(vga));
 
-       if (fb && s->height>=480 && s->width>=640 ) { 
-           uint8_t color = (uint8_t)(vga->updates_since_render);
+    text_start=text;
 
-           uint32_t x, y;
+    // First we need to clip to what we can actually show
+    rtw = tw < fw/cw ? tw : fw/cw;
+    rth = th < fh/ch ? th : fh/ch;
 
-           for (y=0;y<480;y++) {
-               for (x=0;x<640;x++) { 
-                   void *pixel = fb + (x + y*s->width) *s->bytes_per_pixel;
+    
+
+    // Now let's scan by char across the whole thing
+    for (y=0;y<th;y++) { 
+       for (x=0;x<tw;x++, text++, attr++) { 
+           if (x < rtw && y < rth) { 
+               // grab the character and attribute for the position
+               ct = *text; 
+               ca = *attr;  
+               a.val = ca;
+
+               // find the character's font bitmap (one byte per row)
+               find_text_font_start(vga,(void**)&font,
+                                    extended_fontset(vga) ? a.foreground_intensity_or_font_select : 0 ); 
+
+               font += ct * ((VGA_MAX_FONT_HEIGHT * VGA_FONT_WIDTH)/8);
+
+               // Now let's find out what colors we will be using
+               // foreground
+               
+               if (!extended_fontset(vga)) { 
+                   fg_entry = a.foreground_intensity_or_font_select << 3;
+               } else {
+                   fg_entry = 0;
+               }
+               fg_entry |= a.fore;
+
+               find_24bit_color(vga,fg_entry,&fgr,&fgg,&fgb);
+
+               if (!blinking(vga)) { 
+                   bg_entry = a.blinking_or_bg_intensity << 3;
+               } else {
+                   bg_entry = 0;
+               }
+               bg_entry |= a.back;
+               
+               find_24bit_color(vga,bg_entry,&bgr,&bgg,&bgb);
+
+               // Draw the character
+               for (l=0; l<ch; l++, font++) {
+                   uint8_t frow = *font;  // this is the row of of the font map
+                   for (p=0;p<cw;p++) {
+                       uint8_t fbit;
+                       
+                       // a char can be 9 bits wide, but the font map
+                       // is only 8 bits wide, which means we need to know where to
+                       // get the 9th bit
+                       if (p >= 8) { 
+                           // We get it from the font map if
+                           // its line line graphics mode and its a graphics char
+                           // otherwise it's the background color
+                           if (vga->vga_attribute_controller.vga_attribute_mode_control.enable_line_graphics_char_code
+                               && ct>=0xc0 && ct<=0xdf ) { 
+                               fbit = frow & 0x1;
+                           } else {
+                               fbit = 0;
+                           }
+                       } else {
+                           fbit= (frow >> (7-p) ) & 0x1;
+                       }
+                       
+                       // We are now at the pixel level, with fbit being the pixel we draw (color+attr or bg+attr)
+                       // For now, we will draw it as black/white
+
+                       // find its position in the framebuffer;
+                       fx = x*cw + p;
+                       fy = y*ch + l;
+                       pixel =  fb + ((fx + (fy*spec->width)) * spec->bytes_per_pixel);
+                       red = pixel + spec->red_offset;
+                       green = pixel + spec->green_offset;
+                       blue = pixel + spec->blue_offset;
+
+                       // Are we on the cursor?
+                       // if so, let's negate this pixel to invert the cell
+                       if (curs==text) { 
+                           fbit^=0x1;
+                       }
+                       // update the framebuffer
+                       if (fbit) { 
+                           *red=fgr; 
+                           *green=fgg;
+                           *blue=fgb;
+                       } else {
+                           *red=bgr;
+                           *green=bgg;
+                           *blue=bgb;
+                       }
+                   }
+               }
+           }
+       }
+       PrintDebug("\n");
+    }
+
+}
+
+                       
+                       
+
+
+static void render_test(struct vga_internal *vga, void *fb)
+{
+    struct v3_frame_buffer_spec *s;
+
+    s=&(vga->target_spec);
+
+    if (fb && s->height>=480 && s->width>=640 ) { 
+       uint8_t color = (uint8_t)(vga->updates_since_render);
+       
+       uint32_t x, y;
+       
+       for (y=0;y<480;y++) {
+           for (x=0;x<640;x++) { 
+               void *pixel = fb + ((x + (y*s->width)) * s->bytes_per_pixel);
+               uint8_t *red = pixel + s->red_offset;
+               uint8_t *green = pixel + s->green_offset;
+               uint8_t *blue = pixel + s->blue_offset;
+               
+               if (y<(480/4)) { 
+                   *red=color+x;
+                   *green=0;
+                   *blue=0;
+               } else if (y<(480/2)) { 
+                   *red=0;
+                   *green=color+x;
+                   *blue=0;
+               } else if (y<(3*(480/4))) { 
+                   *red=0;
+                   *green=0;
+                   *blue=color+x;
+               } else {
+                   *red=*green=*blue=color+x;
+               }
+           }
+       }
+    }
+}
+
+static void render_black(struct vga_internal *vga, void *fb)
+{
+    struct v3_frame_buffer_spec *s;
+
+    s=&(vga->target_spec);
+
+    memset(fb,0,s->height*s->width*s->bytes_per_pixel);
+}
+
+static void render_maps(struct vga_internal *vga, void *fb)
+{
+
+    struct v3_frame_buffer_spec *s;
+    
+
+    s=&(vga->target_spec);
+
+    if (fb && s->height>=768 && s->width>=1024 && !(vga->updates_since_render % 100)) { 
+       // we draw the maps next, each being a 256x256 block appearing 32 pixels below the display block
+       uint8_t m;
+       uint32_t x,y;
+       uint8_t *b;
+       
+       for (m=0;m<4;m++) { 
+           b=(vga->map[m]);
+           for (y=480+32;y<768;y++) { 
+               for (x=m*256;x<(m+1)*256;x++,b++) { 
+                   void *pixel = fb + ((x + (y*s->width)) * s->bytes_per_pixel);
                    uint8_t *red = pixel + s->red_offset;
                    uint8_t *green = pixel + s->green_offset;
                    uint8_t *blue = pixel + s->blue_offset;
-
-                   if (y<480/4) { 
-                       *red=color+x;
-                       *green=0;
-                       *blue=0;
-                   } else if (y<480/2) { 
-                       *red=0;
-                       *green=color+x;
-                       *blue=0;
-                   } else if (y<3*480/4) { 
-                       *red=0;
-                       *green=0;
-                       *blue=color+x;
-                   } else {
-                       *red=*green=*blue=color+x;
-                   }
+                   
+                   *red=*green=*blue=*b;
                }
            }
        }
     }
+}
+
+
+static int render(struct vga_internal *vga)
+{
+    void *fb;
+
+
+    vga->updates_since_render++;
+
+    if (vga->updates_since_render%100) { 
+       // skip render
+       return 0;
+    }
+
+    if (vga->host_cons && v3_graphics_console_inform_update(vga->host_cons)>0) { 
+
+       fb = v3_graphics_console_get_frame_buffer_data_rw(vga->host_cons,&(vga->target_spec));
+
+       if (!(vga->vga_sequencer.vga_clocking_mode.screen_off)) {
+           if (vga->vga_attribute_controller.vga_attribute_mode_control.graphics) { 
+               render_graphics(vga,fb);
+           } else {
+               render_text(vga,fb);
+               render_text_cursor(vga,fb);
+           }
+       } else {
+           render_black(vga,fb);
+       }
+
+       if (0) { render_test(vga,fb); }
+
+       // always render maps for now 
+       render_maps(vga,fb);
+
+       v3_graphics_console_release_frame_buffer_data_rw(vga->host_cons);
+    }
 
     return 0;
 }
@@ -389,19 +1058,57 @@ static void get_mem_region(struct vga_internal *vga, uint64_t *mem_start, uint64
     }
 }
 
-static uint64_t find_offset(struct vga_internal *vga, addr_t guest_addr)
+static uint64_t find_offset_write(struct vga_internal *vga, addr_t guest_addr)
 {
     uint64_t mem_start, mem_end;
+    uint64_t size;
     
     mem_start=mem_end=0;
     
     get_mem_region(vga, &mem_start, &mem_end);
+    
+    size=(mem_end-mem_start > 65536 ? 65536 : (mem_end-mem_start)); 
 
-    return (guest_addr-mem_start) % (mem_end-mem_start > 65536 ? 65536 : (mem_end-mem_start)); 
-
+    if (vga->vga_sequencer.vga_mem_mode.odd_even) { 
+       return (guest_addr-mem_start) % size;
+    } else {
+       // odd/even mode
+       return ((guest_addr-mem_start) >> 1 ) % size;
+    }
 }
 
+
+
     
+// Determines which maps should be enabled for this single byte write
+// and what the increment (actually 1/increment for the copy loop
+//
+//  memory_mode.odd_even == 0 => even address = maps 0 and 2 enabled; 1,3 otherwise
+//  
+static uint8_t find_map_write(struct vga_internal *vga, addr_t guest_addr)
+{
+    uint8_t mm = vga->vga_sequencer.vga_map_mask.val;
+
+    if (vga->vga_sequencer.vga_mem_mode.odd_even) { 
+       return mm;
+    } else {
+       if (guest_addr & 0x1) { 
+           return mm & 0xa;  // 0x1010
+       } else {
+           return mm & 0x5;  // 0x0101
+       }
+    }
+}
+
+static uint8_t find_increment_write(struct vga_internal *vga, addr_t new_guest_addr)
+{
+    if (vga->vga_sequencer.vga_mem_mode.odd_even) { 
+       return 1;
+    } else {
+       return !(new_guest_addr & 0x1);
+    }
+}
+
 
 
 static int vga_write(struct guest_info * core, 
@@ -410,7 +1117,6 @@ static int vga_write(struct guest_info * core,
                     uint_t length, 
                     void * priv_data)
 {
-    int i;
     struct vm_device *dev = (struct vm_device *)priv_data;
     struct vga_internal *vga = (struct vga_internal *) dev->private_data;
 
@@ -421,15 +1127,24 @@ static int vga_write(struct guest_info * core,
        memcpy(V3_VAddr((void*)guest_addr),src,length);
     }
     
-    PrintDebug("vga: data written was \"");
+#if DEBUG_MEM_DATA
+    int i;
+    PrintDebug("vga: data written was 0x");
+    for (i=0;i<length;i++) {
+       uint8_t c= ((char*)src)[i];
+       PrintDebug("%.2x", c);
+    }
+    PrintDebug(" \"");
     for (i=0;i<length;i++) {
        char c= ((char*)src)[i];
-       PrintDebug("%c", (c>='a' && c<='z') || (c>='A' && c<='Z') || (c>='0' && c<='9') ? c : '.');
+       PrintDebug("%c", (c>='a' && c<='z') || (c>='A' && c<='Z') || (c>='0' && c<='9') || (c==' ') ? c : '.');
     }
     PrintDebug("\"\n");
+#endif
 
     /* Write mode determine by Graphics Mode Register (Index 05h).writemode */
-    
+
+
     switch (vga->vga_graphics_controller.vga_graphics_mode.write_mode) {
        case 0: {
            
@@ -452,30 +1167,49 @@ static int vga_write(struct guest_info * core,
            uint8_t ror = vga->vga_graphics_controller.vga_data_rotate.rotate_count;
            uint8_t func = vga->vga_graphics_controller.vga_data_rotate.function;
            
-           offset = find_offset(vga, guest_addr);
+           offset = find_offset_write(vga, guest_addr);
 
+#if DEBUG_DEEP_MEM
            PrintDebug("vga: mode 0 write, offset=0x%llx, ror=%u, func=%u\n", offset,ror,func);
+#endif
 
-           for (i=0;i<length;i++,offset++) { 
+           for (i=0;i<length;i++,offset+=find_increment_write(vga,guest_addr+i)) { 
                // now for each map
                uint8_t sr = vga->vga_graphics_controller.vga_set_reset.val & 0xf;
                uint8_t esr = vga->vga_graphics_controller.vga_enable_set_reset.val &0xf;
                uint8_t bm = vga->vga_graphics_controller.vga_bit_mask;
-               uint8_t mm = vga->vga_sequencer.vga_map_mask.val;
+               uint8_t mm = find_map_write(vga,guest_addr+i);
+
+#if DEBUG_DEEP_MEM
+               PrintDebug("vga: write i=%u, mm=0x%x, bm=0x%x sr=0x%x esr=0x%x offset=0x%x\n",i,(unsigned int)mm,(unsigned int)bm, (unsigned int)sr, (unsigned int)esr,(unsigned int)offset);
+#endif
 
-               for (mapnum=0;mapnum<4;mapnum++, sr>>=1, esr>>=1, bm>>=1, mm>>=1) { 
+               for (mapnum=0;mapnum<4;mapnum++, sr>>=1, esr>>=1, mm>>=1) { 
                    vga_map map = vga->map[mapnum];
                    uint8_t data = ((uint8_t *)src)[i];
                    uint8_t latchval = vga->latch[mapnum];
-                       
+                   
+#if DEBUG_DEEP_MEM
+                   PrintDebug("vga: raw data=0x%x\n",data);
+#endif
                    // rotate data right
-                   data = (data>>ror) | data<<(8-ror);
-
+                   if (ror) { 
+                       data = (data>>ror) | (data<<(8-ror));
+                   }
+                   
+#if DEBUG_DEEP_MEM
+                   PrintDebug("vga: data after ror=0x%x\n",data);
+#endif
                    // use SR bit if ESR is on for this map
-                   if (esr & 0x1) { 
-                       data = (uint8_t)((((sint8_t)(sr&0x1))<<7)>>7);  // expand sr bit
+                   if (esr & 0x1) {
+                       data = (sr&0x1) * -1;
+                       
                    }
                    
+#if DEBUG_DEEP_MEM
+                   PrintDebug("vga: data after esrr=0x%x\n",data);
+#endif
+                   
                    // Apply function
                    switch (func) { 
                        case 0: // NOP
@@ -490,19 +1224,26 @@ static int vga_write(struct guest_info * core,
                            data ^= latchval;
                            break;
                    }
-                           
-                   // mux between latch and alu output
-                   if (bm & 0x1) { 
-                       // use alu output, which is in data
-                   } else {
-                       // use latch value
-                       data=latchval;
-                   }
+                   
+#if DEBUG_DEEP_MEM
+                   PrintDebug("vga: data after func=0x%x\n",data);
+#endif
+                   
+                   // mux between the data byte and the latch byte on
+                   // a per-bit basis
+                   data = (bm & data) | ((~bm) & latchval);
+                   
+
+#if DEBUG_DEEP_MEM
+                   PrintDebug("vga: data after bm mux=0x%x\n",data);
+#endif
                    
                    // selective write
                    if (mm & 0x1) { 
                        // write to this map
-                       //PrintDebug("vga: write map %u offset 0x%p map=0x%p pointer=0x%p\n",mapnum,(void*)offset,map,&(map[offset]));
+#if DEBUG_DEEP_MEM
+                       PrintDebug("vga: write map %u offset 0x%p map=0x%p pointer=0x%p\n",mapnum,(void*)offset,map,&(map[offset]));
+#endif
                        map[offset] = data;
                    } else {
                        // skip this map
@@ -523,14 +1264,16 @@ static int vga_write(struct guest_info * core,
 
            int i;
 
-           uint64_t offset = find_offset(vga,guest_addr);
+           uint64_t offset = find_offset_write(vga,guest_addr);
 
+#if DEBUG_DEEP_MEM
            PrintDebug("vga: mode 1 write, offset=0x%llx\n", offset);
+#endif
 
-           for (i=0;i<length;i++,offset++) { 
+           for (i=0;i<length;i++,offset+=find_increment_write(vga,guest_addr+i)) { 
 
                uint8_t mapnum;
-               uint8_t mm = vga->vga_sequencer.vga_map_mask.val;
+               uint8_t mm = find_map_write(vga,guest_addr+i);
 
                for (mapnum=0;mapnum<4;mapnum++,  mm>>=1) { 
                    vga_map map = vga->map[mapnum];
@@ -564,14 +1307,16 @@ static int vga_write(struct guest_info * core,
 
            uint8_t func = vga->vga_graphics_controller.vga_data_rotate.function;
            
-           offset = find_offset(vga, guest_addr);
+           offset = find_offset_write(vga, guest_addr);
 
+#if DEBUG_DEEP_MEM
            PrintDebug("vga: mode 2 write, offset=0x%llx, func=%u\n", offset,func);
+#endif
 
-           for (i=0;i<length;i++,offset++) { 
+           for (i=0;i<length;i++,offset+=find_increment_write(vga,guest_addr+i)) { 
                // now for each map
                uint8_t bm = vga->vga_graphics_controller.vga_bit_mask;
-               uint8_t mm = vga->vga_sequencer.vga_map_mask.val;
+               uint8_t mm = find_map_write(vga,guest_addr+i);
 
                for (mapnum=0;mapnum<4;mapnum++,  bm>>=1, mm>>=1) { 
                    vga_map map = vga->map[mapnum];
@@ -579,9 +1324,9 @@ static int vga_write(struct guest_info * core,
                    uint8_t latchval = vga->latch[mapnum];
                        
                    // expand relevant bit to 8 bit
-                   // it's basically esr=1, sr=bit from write
-                   data = (uint8_t)(((sint8_t)(((data>>mapnum)&0x1)<<7))>>7);
-                   
+                   // it's basically esr=1, sr=bit from mode 0 write
+                   data = ((data>>mapnum)&0x1) * -1;
+                       
                    // Apply function
                    switch (func) { 
                        case 0: // NOP
@@ -596,14 +1341,9 @@ static int vga_write(struct guest_info * core,
                            data ^= latchval;
                            break;
                    }
-                           
+
                    // mux between latch and alu output
-                   if (bm & 0x1) { 
-                       // use alu output, which is in data
-                   } else {
-                       // use latch value
-                       data=latchval;
-                   }
+                   data = (bm & data) | ((~bm) & latchval);
                    
                    // selective write
                    if (mm & 0x1) { 
@@ -635,34 +1375,31 @@ static int vga_write(struct guest_info * core,
 
            uint8_t ror = vga->vga_graphics_controller.vga_data_rotate.rotate_count;
            
-           offset = find_offset(vga, guest_addr);
+           offset = find_offset_write(vga, guest_addr);
 
            PrintDebug("vga: mode 3 write, offset=0x%llx, ror=%u\n", offset,ror);
 
-           for (i=0;i<length;i++,offset++) { 
+           for (i=0;i<length;i++,offset+=find_increment_write(vga,guest_addr+i)) { 
                // now for each map
                uint8_t data = ((uint8_t *)src)[i];
 
-               data = (data>>ror) | data<<(8-ror);
+               if (ror) {
+                   data = (data>>ror) | (data<<(8-ror));
+               }
 
                uint8_t bm = vga->vga_graphics_controller.vga_bit_mask & data;
                uint8_t sr = vga->vga_graphics_controller.vga_set_reset.val & 0xf;
-               uint8_t mm = vga->vga_sequencer.vga_map_mask.val;
+               uint8_t mm = find_map_write(vga,guest_addr+i);
 
                for (mapnum=0;mapnum<4;mapnum++, sr>>=1, bm>>=1, mm>>=1) { 
                    vga_map map = vga->map[mapnum];
                    uint8_t latchval = vga->latch[mapnum];
                        
-                   data = (uint8_t)((((sint8_t)(sr&0x1))<<7)>>7);  // expand sr bit
-                   
-                   
+                   // expand SR bit
+                   data = (sr&0x1) * -1;
+
                    // mux between latch and alu output
-                   if (bm & 0x1) { 
-                       // use alu output, which is in data
-                   } else {
-                       // use latch value
-                       data=latchval;
-                   }
+                   data = (bm & data) | ((~bm) & latchval);
                    
                    // selective write
                    if (mm & 0x1) { 
@@ -686,44 +1423,35 @@ static int vga_write(struct guest_info * core,
 }
 
 
-/*
-up to 256K mapped through a window of 32 to 128K
-
-most cards support linear mode as well
-
-Need to implement readability too
-
-Write extended memory bit to enable all 256K: 
-
-   Sequencer Memory Mode Register (Index 04h) . extended memory
-
-Must enable writes before effects happen:
-  
-  Miscellaneous Output Register (Read at 3CCh, Write at 3C2h).ram enable
-
-Choose which addresses are supported for CPU writes:
-
-Miscellaneous Graphics Register (Index 06h).memory map select
-00b -- A0000h-BFFFFh (128K region)
-01b -- A0000h-AFFFFh (64K region)
-10b -- B0000h-B7FFFh (32K region)
-11b -- B8000h-BFFFFh (32K region)
-
-There are three addressing modes: Chain 4, Odd/Even mode, and normal mode:
-
-Chain 4: This mode is used for MCGA emulation in the 320x200 256-color mode. The address is mapped to memory MOD 4 (shifted right 2 places.)
-
-Memory model: 64K 32 bit locations; divided into 4 64K bit planes
-
-
-   
 
+static uint64_t find_offset_read(struct vga_internal *vga, addr_t guest_addr)
+{
+    uint64_t mem_start, mem_end;
+    uint64_t size;
+    
+    mem_start=mem_end=0;
+    
+    get_mem_region(vga, &mem_start, &mem_end);
+    
+    size=(mem_end-mem_start > 65536 ? 65536 : (mem_end-mem_start)); 
 
-Assume linear framebuffer, starting at address buf:
+    if (!vga->vga_sequencer.vga_mem_mode.chain4) { 
+       return (guest_addr-mem_start) % size;
+    } else {
+       // chain4 mode
+       return ((guest_addr - mem_start) >> 2) % size;
+    }
+}
 
-*/
+static uint8_t find_increment_read(struct vga_internal *vga, addr_t new_guest_addr)
+{
 
+    if (vga->vga_sequencer.vga_mem_mode.chain4) { 
+       return !(new_guest_addr & 0x3);
+    } else {
+       return 1;
+    }
+}
 
 
 static int vga_read(struct guest_info * core, 
@@ -732,15 +1460,13 @@ static int vga_read(struct guest_info * core,
                    uint_t length, 
                    void * priv_data)
 {
-    int i;
     struct vm_device *dev = (struct vm_device *)priv_data;
     struct vga_internal *vga = (struct vga_internal *) dev->private_data;
     
 
     PrintDebug("vga: memory read: guest_addr=0x%p len=%u\n",(void*)guest_addr, length);
 
-
-               
+        
    
     /*
       Reading, 2 modes, set via Graphics Mode Register (index 05h).Read Mode:
@@ -751,21 +1477,43 @@ static int vga_read(struct guest_info * core,
                    which plane is determined by Read Map Select (Read Map Select Register (Index 04h)) */
            uint8_t  mapnum;
            uint64_t offset;
-           
-           mapnum = vga->vga_graphics_controller.vga_read_map_select.map_select;
-           offset = find_offset(vga,guest_addr);
-           
-           if (offset>=65536) { 
-               PrintError("vga: read to offset=%llu map=%u (%u bytes)\n",offset,mapnum,length);
-           }
 
-           memcpy(dst,(vga->map[mapnum])+offset,length);
 
-           // load the latches with the last item read
-           for (mapnum=0;mapnum<4;mapnum++) { 
-               vga->latch[mapnum] = vga->map[mapnum][offset+length-1];
+           if (vga->vga_sequencer.vga_mem_mode.chain4) { 
+               uint32_t i;
+               offset = find_offset_read(vga,guest_addr);
+               // address bytes select the map
+               for (i=0;i<length;i++,offset+=find_increment_read(vga,guest_addr+i)) { 
+                   mapnum = (guest_addr+i) % 4;
+#if DEBUG_DEEP_MEM
+                   PrintDebug("vga: mode 0 read, chain4, offset=0x%llx, mapnum=%u\n",offset,mapnum);
+#endif
+                   ((uint8_t*)dst)[i] = *(vga->map[mapnum]+offset);
+
+                   // presumably all the latches are to be reloaded, not just the selected one?
+                   for (mapnum=0;mapnum<4;mapnum++) { 
+                       vga->latch[mapnum] = *(vga->map[mapnum]+offset);
+                   }
+               }
+           } else {
+               mapnum = vga->vga_graphics_controller.vga_read_map_select.map_select;
+               offset = find_offset_read(vga,guest_addr);
+               
+               if (offset>=65536) { 
+                   PrintError("vga: read to offset=%llu map=%u (%u bytes)\n",offset,mapnum,length);
+               }
+               
+#if DEBUG_DEEP_MEM
+               PrintDebug("vga: mode 0 read, not-chain4, offset=0x%llx, mapnum=%u\n",offset,mapnum);
+#endif
+
+               memcpy(dst,(vga->map[mapnum])+offset,length);
+               
+               // load the latches with the last item read
+               for (mapnum=0;mapnum<4;mapnum++) { 
+                   vga->latch[mapnum] = vga->map[mapnum][offset+length-1];
+               }
            }
-           
        
        }
            break;
@@ -788,7 +1536,12 @@ static int vga_read(struct guest_info * core,
            uint8_t  byte;
            uint8_t  bits;
            
-           offset = find_offset(vga,guest_addr);
+           offset = find_offset_read(vga,guest_addr);
+
+#if DEBUG_DEEP_MEM
+           PrintDebug("vga: mode 1 read, offset=0x%llx, cc=0x%x, dc-0x%x\n",offset,cc,dc);
+#endif
+               
            
            for (i=0;i<length;i++,offset++) { 
                vga_map map;
@@ -826,12 +1579,20 @@ static int vga_read(struct guest_info * core,
     }
 
 
-    PrintDebug("vga: data read is \"");
+#if DEBUG_MEM_DATA
+    int i;
+    PrintDebug("vga: data read is 0x");
+    for (i=0;i<length;i++) {
+       uint8_t c= ((char*)dst)[i];
+       PrintDebug("%.2x", c);
+    }
+    PrintDebug(" \"");
     for (i=0;i<length;i++) {
        char c= ((char*)dst)[i];
-       PrintDebug("%c", (c>='a' && c<='z') || (c>='A' && c<='Z') || (c>='0' && c<='9') ? c : '.');
+       PrintDebug("%c", (c>='a' && c<='z') || (c>='A' && c<='Z') || (c>='0' && c<='9') || (c==' ') ? c : '.');
     }
     PrintDebug("\"\n");
+#endif
 
     return length;