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46 lines
1.0 KiB
ArmAsm
46 lines
1.0 KiB
ArmAsm
// Arm assembly to copy the Gemini kernel on Storlink reference
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// designs and derived devices with the same flash layout and
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// boot loader.
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//
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// This will execute at 0x01600000
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//
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// Copies the kernel from two fragments (originally zImage
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// and initramdisk) to 0x00400000 making space for a kernel
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// image of up to 8 MB except for these 512 bytes used for
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// this bootstrap.
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//
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// 0x01600200 .. 0x017fffff -> 0x00400000 .. 0x005ffdff
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// 0x00800000 .. 0x00dfffff -> 0x005ffe00 .. 0x00bffdff
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// Memory used for this bootstrap
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.equ BOOT_HEADROOM, 0x200
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.global _start // Stand-alone assembly code
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_start:
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mov r1, #0x01600000
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mov r2, #0x00400000
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mov r3, #0x00200000
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add r1, r1, #BOOT_HEADROOM
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sub r3, r3, #BOOT_HEADROOM
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copyloop1:
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ldr r0, [r1]
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str r0, [r2]
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add r1, r1, #4
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add r2, r2, #4
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sub r3, r3, #4
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cmp r3, #0
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bne copyloop1
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mov r1, #0x00800000
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mov r3, #0x00600000
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copyloop2:
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ldr r0, [r1]
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str r0, [r2]
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add r1, r1, #4
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add r2, r2, #4
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sub r3, r3, #4
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cmp r3, #0
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bne copyloop2
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mov r0, #0x00400000
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// Let's go
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mov pc, r0
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