RAM

; Copyright 2009 Castle Technology Ltd
;
; Licensed under the Apache License, Version 2.0 (the "License");
; you may not use this file except in compliance with the License.
; You may obtain a copy of the License at
;
;     http://www.apache.org/licenses/LICENSE-2.0
;
; Unless required by applicable law or agreed to in writing, software
; distributed under the License is distributed on an "AS IS" BASIS,
; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
; See the License for the specific language governing permissions and
; limitations under the License.
;
; a1 <= Highest physical address in RAM +1
get_end_of_ram
        LDR     v1, =SDRC_Regs
        LDR     a3, [v1, #SDRC_MCFG_1]
        LDR     a2, =&3FF00<<13
        ANDS    a3, a2, a3, LSL #13
        BEQ     %FT10
        LDR     a2, =CS1_SDRAM
        LDR     a4, [v1, #SDRC_CS_CFG]
        AND     v2, a4, #7 ; Offset in 128MB units
        ADD     a2, a2, v2, LSL #20+7
        AND     v2, a4, #&300 ; Offset in 32MB units
        ADD     a2, a2, v2, LSL #20+5-8
        ADD     a1, a3, a2
        MOV     pc, lr
10
        ; No RAM in CS1; therefore must be in CS0
        LDR     a3, [v1, #SDRC_MCFG_0]
        LDR     a2, =&3FF00<<13
        AND     a3, a2, a3, LSL #13 ; Get CS0 RAM size
        LDR     a2, =CS0_SDRAM
        ADD     a1, a3, a2
        MOV     pc, lr


clear_ram
        ; Clear everything up to a1
        MOV     v2, a1
        LDR     v1, =SDRC_Regs
        LDR     a3, [v1, #SDRC_MCFG_0]
        LDR     a2, =&3FF00<<13
        ANDS    a3, a2, a3, LSL #13 ; Get CS0 RAM size
        BEQ     %FT10
        LDR     a2, =CS0_SDRAM
        SUB     a1, v2, a2
        CMP     a1, a3
        MOVGT   a1, a3 ; Work out how much we're meant to be clearing
        MOV     a3, #0
20
        STR     a3, [a2], #4
        SUBS    a1, a1, #4
        BGT     %BT20
10
        LDR     a3, [v1, #SDRC_MCFG_1]
        LDR     a2, =&3FF00<<13
        ANDS    a3, a2, a3, LSL #13
        BEQ     %FT30
        LDR     a2, =CS1_SDRAM
        LDR     a4, [v1, #SDRC_CS_CFG]
        AND     v2, a4, #7 ; Offset in 128MB units
        ADD     a2, a2, v2, LSL #20+7
        AND     v2, a4, #&300 ; Offset in 32MB units
        ADD     a2, a2, v2, LSL #20+5-8
        SUB     a1, v2, a2
        CMP     a1, a3
        MOVGT   a1, a3 ; Work out how much we're meant to be clearing
        MOV     a3, #0
40
        STR     a3, [a2], #4
        SUBS    a1, a1, #4
        BGT     %BT40
30
        MOV     pc, lr

        END