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improved comments, added a FIXME (needs checking). Probably video page copy is called too often

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This commit is contained in:
Markus Fröschle
2013-10-30 14:17:54 +00:00
parent 98c81ad230
commit 919e221b4a
1 changed files with 214 additions and 217 deletions
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33
BaS_gcc/sources/mmu.S
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@@ -119,7 +119,7 @@ _mmu_init:
move.l d0,MCF_MMU_MMUOR
nop
// 0000'0000 locked
// 0000'0000 - 000F'FFFF (first megabyte of physical memory) locked virtual = physical
moveq.l #0x00000000|std_mmutr,d0
moveq.l #0x00000000|copyback_mmudr|MCF_MMU_MMUDR_LK,d1
moveq.l #mmuord_d,d2 // MMU update data
@@ -129,24 +129,24 @@ _mmu_init:
move.l d2,MCF_MMU_MMUOR // MMU update data
move.l d3,MCF_MMU_MMUOR // MMU update instruction
//---------------------------------------------------------------------------------------
// 00d0'0000 locked ID=6
// 00D0'0000 - 0x00DF'FFFF (last megabyte of ST RAM = Falcon video memory) locked ID=6
// mapped to physical address 60D0'0000 (FPGA video memory)
// video ram: read write execute normal write true
move.l #0x00d00000|MCF_MMU_MMUTR_ID(sca_page_ID)|std_mmutr,d0
move.l #0x60d00000|writethrough_mmudr|MCF_MMU_MMUDR_LK,d1
move.l d0,MCF_MMU_MMUTR
move.l d1,MCF_MMU_MMUDR
move.l d2,MCF_MMU_MMUOR // MMU update data
move.l d2,MCF_MMU_MMUOR // MMU update data
move.l #0x00d00000|std_mmutr,d0
move.l d3,MCF_MMU_MMUOR // MMU update instruction
move.l d3,MCF_MMU_MMUOR // MMU update instruction
move.l #0x2000,d0
move.l d0,_video_tlb // set page as video page
clr.l _video_sbt // clear time
move.l d0,_video_tlb // set page as video page
clr.l _video_sbt // clear time
// create locked TLB entries which must be available as soon as the MMU gets enabled
// Make the TOS (in SDRAM) read-only
// this maps virtual 0x00E0'0000-0x00EF'FFFF to the same physical address
move.l #__TOS+std_mmutr,d0
move.l #__TOS+copyback_mmudr+MCF_MMU_MMUDR_LK,d1
move.l d0,MCF_MMU_MMUTR
@@ -155,6 +155,8 @@ _mmu_init:
move.l d3,MCF_MMU_MMUOR // setzen
// 00f0'0000 locked
// this maps virtual 0x00F0'0000 - 0x00FF'FFFF to physical 0xFFF0'0000 - 0xFFFF'FFFF effectively making I/O area
// accesses ST-compatible (just the same what Atari made for TT and Falcon)
move.l #0x00f00000|std_mmutr,d0
move.l #0xfff00000|nocache_precise_mmudr|MCF_MMU_MMUDR_LK,d1
move.l d0,MCF_MMU_MMUTR
@@ -163,25 +165,20 @@ _mmu_init:
move.l d3,MCF_MMU_MMUOR // mapped to ffffxxx, precise,
// 1ff0'0000 locked
move.l #0x1FF00000|std_mmutr,d0 // last megabyte of RAM. Reserved for BaS
// maps virtual 0x1FF0'0000 - 0x1FFF'FFFF to the same physical address
move.l #0x1FF00000|std_mmutr,d0 // last megabyte of physical RAM. Reserved for BaS
move.l #0x1FF00000|copyback_mmudr|MCF_MMU_MMUDR_LK,d1
move.l d0,MCF_MMU_MMUTR
move.l d1,MCF_MMU_MMUDR
move.l d2,MCF_MMU_MMUOR // setzen data
move.l d3,MCF_MMU_MMUOR // setzen instr
// instr 0xFFF0'0000 nach 0x1FF0'0000 umleiten -->> short sprung
/* move.l #0xFFF00000|std_mmutr,d0
move.l #0x1FF00000|copyback_mmudr|MCF_MMU_MMUDR_LK,d1
move.l d0,MCF_MMU_MMUTR
move.l d1,MCF_MMU_MMUDR
move.l d3,MCF_MMU_MMUOR // setzen instr
*/
move.l (sp)+,d2 // Restore registers
move.l (sp)+,d3
rts
/*
* MMU table add on miss
* Everything else gets a 1:1 mapping on miss
*/
_mmutr_miss:
lea -8 * 4(sp),sp
@@ -202,7 +199,7 @@ _mmutr_miss:
move.l d0,MCF_MMU_MMUTR // add to TLB
and.l #0xFFF00000,d0 // mask out page
or.l #copyback_mmudr,d0 // 1MB page size, cachable copyback, read, write, execute
move.l d0,MCF_MMU_MMUDR // add to TLB
move.l d0,MCF_MMU_MMUDR // add physical address to TLB
moveq.l #mmuord_d,d0 // MMU update data
move.l d0,MCF_MMU_MMUOR // set
moveq.l #mmuord_i,d0 // MMU update instruction