mirror of https://github.com/mgcaret/of816.git
57 lines
2.1 KiB
ArmAsm
57 lines
2.1 KiB
ArmAsm
; Platform support dictionary words for WDC W65C816SXB
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;
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; This file serves as a "reference implementation" for how to do this.
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; ROM read. This will read from the SXB's flash ROM, from any bank.
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; Requires memmgr.s to have the memory move routines and platform-lib.s to have
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; _sxb_readrom
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; Since we expect the Forth interpreter to be in the ROM, this works by copying the
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; _sxb_readrom routine into allocated RAM and executing it from there using RTL tricks.
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; H: ( rom_addr dest_addr size ) rom_addr is a 'virtual' address of bb00xxxx
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dword SXB_READROM,"$SXB-READROM"
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ENTER
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ONLIT _sxb_readrom ; ( -- a-addr )
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ONLIT .sizeof(_sxb_readrom) ; ( a-addr -- a-addr u )
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.dword DUP ; ( ... a-addr u u' )
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.dword ALLOC ; ( ... a-addr1 u a-addr2 )
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.dword DUP ; ( ... a-addr1 u a-addr2 a-addr2' )
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.dword PtoR ; ( ... a-addr1 u a-addr2 )
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.dword SWAP ; ( ... a-addr1 a-addr2 u )
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.dword MOVE ; ( a-addr1 a-addr2 u -- ) move code into place
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.dword RCOPY ; ( -- a-addr2' )
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CODE
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jsr _popay ; set up a JML to allocated routine
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sty ZR+1
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sep #SHORT_A
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.a8
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sta ZR+3
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lda #opJML
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sta ZR
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rep #SHORT_A
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.a16
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jsr _popxr ; pop read arguments from the stack
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jsr _popyr ; into the correct working registers
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jsr _popwr
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jsl f:_callzr ; and call the allocated routine
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ENTER
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.dword RtoP ; pull allocation off stack
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ONLIT .sizeof(_sxb_readrom)
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.dword FREE ; and free it
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EXIT
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eword
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dword dCPU_HZ,"$CPU_HZ"
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FCONSTANT cpu_clk
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eword
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.if include_fcode ; SXB stuff, should do different
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dword SXB_ROMLDR,"$SXB-ROMLDR"
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ENTER
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ONLIT :+
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.dword ONE
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.dword BYTE_LOAD
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EXIT
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: PLATFORM_INCBIN "fcode/romloader.fc"
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eword
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.endif
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