105 lines
2.8 KiB
Lua
105 lines
2.8 KiB
Lua
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-- create the module's table
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local snes = {}
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-- import required modules
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local dict = require "scripts.app.dict"
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-- file constants
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local RESET_VECT_HI = 0xFFFD
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local RESET_VECT_LO = 0xFFFC
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-- local functions
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-- Desc:read reset vector from passed in bank
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-- Pre: snes_init() been called to setup i/o
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-- Post:Address left on bus memories disabled
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-- Rtn: reset vector that was found
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local function read_reset_vector( bank, debug )
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--ensure cart is in play mode
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dict.pinport("CTL_SET_HI", "SNES_RST")
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--first set SNES bank A16-23
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dict.snes("SNES_SET_BANK", bank)
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--read reset vector high byte
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vector = dict.snes("SNES_ROM_RD", RESET_VECT_HI)
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--shift high byte of vector to where it belongs
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vector = vector << 8
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--read low byte of vector
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vector = vector | dict.snes("SNES_ROM_RD", RESET_VECT_LO)
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if debug then print("SNES bank:", bank, "reset vector", string.format("$%x", vector) ) end
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return vector
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end
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-- Desc: attempt to read flash rom ID
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-- Pre: snes_init() been called to setup i/o
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-- Post:Address left on bus memories disabled
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-- Rtn: true if flash ID found
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local function read_flashID( debug )
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local rv
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--enter software mode A11 is highest address bit that needs to be valid
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--datasheet not exactly explicit, A11 might not need to be valid
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--part has A-1 (negative 1) since it's in byte mode, meaning the part's A11 is actually A12
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--WR $AAA:AA $555:55 $AAA:AA
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dict.snes("SNES_SET_BANK", 0x00)
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--put cart in program mode
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dict.pinport("CTL_SET_LO", "SNES_RST")
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dict.snes("SNES_ROM_WR", 0x0AAA, 0xAA)
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dict.snes("SNES_ROM_WR", 0x0555, 0x55)
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dict.snes("SNES_ROM_WR", 0x0AAA, 0x90)
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--exit program mode
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dict.pinport("CTL_SET_HI", "SNES_RST")
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--read manf ID
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local manf_id = dict.snes("SNES_ROM_RD", 0x0000)
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if debug then print("attempted read SNES ROM manf ID:", string.format("%X", manf_id)) end
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--read prod ID
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local prod_id = dict.snes("SNES_ROM_RD", 0x0002)
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if debug then print("attempted read SNES ROM prod ID:", string.format("%X", prod_id)) end
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local density_id = dict.snes("SNES_ROM_RD", 0x001C)
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if debug then print("attempted read SNES density ID: ", string.format("%X", density_id)) end
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local boot_sect = dict.snes("SNES_ROM_RD", 0x001E)
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if debug then print("attempted read SNES boot sect ID:", string.format("%X", boot_sect)) end
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--put cart in program mode
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dict.pinport("CTL_SET_LO", "SNES_RST")
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--exit software
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dict.snes("SNES_ROM_WR", 0x0000, 0xF0)
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--exit program mode
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dict.pinport("CTL_SET_HI", "SNES_RST")
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--return true if detected flash chip
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if (manf_id == 0x01 and prod_id == 0x49) then
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return true
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else
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return false
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end
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end
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-- global variables so other modules can use them
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-- call functions desired to run when script is called/imported
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-- functions other modules are able to call
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snes.read_reset_vector = read_reset_vector
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snes.read_flashID = read_flashID
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-- return the module's table
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return snes
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