forked from KolibriOS/kolibrios
63 lines
1.7 KiB
PHP
63 lines
1.7 KiB
PHP
iglobal
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prev_user_of_fpu dd 0x1 ; set to OS
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endg
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label fpu_tss at 0xB080
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label fpu_stack dword at 0xB060
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align 4
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fpu_handler:
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; clear TS flag in CR0 -> for task switching
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clts
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; save FPU context of the previous task
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mov eax,[prev_user_of_fpu]
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shl eax,8
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add eax,0x80000+0x10
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fsave [eax]
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; next task switch save our FPU context
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; now restore context of current task (if exists)
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mov eax,[0x3000]
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mov [prev_user_of_fpu],eax
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shl eax,8
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add eax,0x80000
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cmp [eax+0x7f],byte 0
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je bs7_first_fpu
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frstor [eax+0x10]
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bs7_first_fpu:
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mov [eax+0x7f],byte 1
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; prepare structure in stack for proper IRET
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movzx eax,word [fpu_tss+l.ss-tss_sceleton] ; push ss
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push eax
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mov eax,[fpu_tss+l.esp-tss_sceleton] ; push esp
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push eax
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mov eax,[fpu_tss+l.eflags-tss_sceleton] ; push eflags
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push eax
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movzx eax,word [fpu_tss+l.cs-tss_sceleton] ; push cs
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push eax
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mov eax,[fpu_tss+l.eip-tss_sceleton] ; push eip
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push eax
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; save eax
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push dword [fpu_tss+l.eax-tss_sceleton]
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; restore all segment registers
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mov ax,[fpu_tss+l.es-tss_sceleton]
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mov es,ax
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mov ax,[fpu_tss+l.fs-tss_sceleton]
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mov fs,ax
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mov ax,[fpu_tss+l.gs-tss_sceleton]
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mov gs,ax
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mov ax,[fpu_tss+l.ds-tss_sceleton]
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mov ds,ax
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; restore eax
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pop eax
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iret
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