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PC-98 GDC: CMD_TEXTW is the same as parameter byte 8, combine the code. Do not treat it differently than plain parameter RAM load. Still has not solved problems with Windows 3.1

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This commit is contained in:
Jonathan Campbell 2022-05-24 13:14:01 -07:00
parent 95d23e2f95
commit 484cd43093
2 changed files with 12 additions and 10 deletions
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2
include/pc98_gdc_const.h
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@ -18,6 +18,6 @@ enum {
GDC_CMD_VECTE = 0x6c, // 0 1 1 0 1 1 0 0
GDC_CMD_VERTICAL_SYNC_MODE = 0x6E, // 0 1 1 0 1 1 1 M
GDC_CMD_PARAMETER_RAM_LOAD = 0x70, // 0 1 1 1 S S S S S[3:0] = starting address in parameter RAM
GDC_CMD_TEXTW = 0x78, // 0 1 1 1 1 0 0 0
GDC_CMD_TEXTW = 0x78, // 0 1 1 1 1 0 0 0 This is the same as GDC_CMD_PARAMETER_RAM_LOAD+8 aka loading at the 8th byte
GDC_CMD_CURSOR_ADDRESS_READ = 0xE0 // 1 1 1 0 0 0 0 0
};

20
src/hardware/vga_pc98_gdc.cpp
View File

@ -400,10 +400,8 @@ void PC98_GDC_state::idle_proc(void) {
case GDC_CMD_PARAMETER_RAM_LOAD+13:// 0x7D S=starting byte in parameter RAM
case GDC_CMD_PARAMETER_RAM_LOAD+14:// 0x7E S=starting byte in parameter RAM
case GDC_CMD_PARAMETER_RAM_LOAD+15:// 0x7F S=starting byte in parameter RAM
if(master_sync || current_command != GDC_CMD_TEXTW) {
param_ram_wptr = current_command & 0xF;
current_command = GDC_CMD_PARAMETER_RAM_LOAD;
}
param_ram_wptr = current_command & 0xF;
current_command = GDC_CMD_PARAMETER_RAM_LOAD;
break;
case GDC_CMD_CURSOR_ADDRESS_READ: // 0xE0 1 1 1 0 0 0 0 0
write_rfifo((unsigned char)( vga.config.cursor_start & 0xFFu));
@ -452,11 +450,6 @@ void PC98_GDC_state::idle_proc(void) {
vectw(proc_step);
}
break;
case GDC_CMD_TEXTW:
if(proc_step < 8) {
draw.tx[proc_step++] = (uint8_t)val;
}
break;
case GDC_CMD_CURSOR_CHAR_SETUP:
if (proc_step < 3) {
cmd_parm_tmp[proc_step++] = (uint8_t)val;
@ -466,6 +459,15 @@ void PC98_GDC_state::idle_proc(void) {
}
break;
case GDC_CMD_PARAMETER_RAM_LOAD:
/* Parameter bytes 8 and 9 hold the 16-bit pattern for graphics.
* nanshiki's original code seems to imply that somehow the hardware
* supports either a 64-bit pattern across the 8 bytes or 4 16-bit
* patterns across the same. Given that a few PC-9821 games exploit
* a bug in older hardware to get 4 display partitions in graphics,
* that wouldn't surprise me.
*
* PC-98 Windows 3.1 requires us to do this or else lines do not draw properly. */
if (param_ram_wptr >= 8 && param_ram_wptr <= 15) draw.tx[param_ram_wptr-8] = (uint8_t)val;
param_ram[param_ram_wptr] = (uint8_t)val;
if ((++param_ram_wptr) >= 16) param_ram_wptr = 0;
break;