mirror of https://github.com/YosysHQ/picorv32.git
57 lines
1.0 KiB
ArmAsm
57 lines
1.0 KiB
ArmAsm
# write RAM code (a sequence of nops followed by ret)
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li x5,0x00000013 # nop
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sw x5,4(x0)
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sw x5,8(x0)
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sw x5,12(x0)
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sw x5,16(x0)
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sw x5,20(x0)
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sw x5,24(x0)
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sw x5,28(x0)
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sw x5,32(x0)
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sw x5,36(x0)
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sw x5,40(x0)
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sw x5,44(x0)
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sw x5,48(x0)
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sw x5,52(x0)
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sw x5,56(x0)
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sw x5,60(x0)
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sw x5,64(x0)
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sw x5,68(x0)
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sw x5,72(x0)
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sw x5,76(x0)
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li x5,0x00008067 # ret
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sw x5,80(x0)
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# setup gpio address in x5
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li x5,0xc0000000
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sw x0,0(x5)
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# initial entry point into RAM code
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li x3,4
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# initialize RAM counter
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sw x0,0(x0)
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# start of loop. remember this address
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auipc x4,0
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# execute RAM code, come back here
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jalr x3
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# load counter and increment
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lw x6,0(x0)
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addi x6,x6,1
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# store counter and update gpios
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sw x6,0(x5)
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sw x6,0(x0)
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# calculate new entry point into RAM code
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slli x3,x6,2
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andi x3,x3,63
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addi x3,x3,4
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# execute RAM code, come back to start of loop
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mv x1,x4
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jr x3
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