initial commit

FIRMWARE/start_spiflash1.S

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+.equ IO_BASE, 0x400000  
+
+.text
+.global _start
+.type _start, @function
+
+_start:
+.option push
+.option norelax
+     li  gp,IO_BASE
+.option pop
+
+     li   sp,0x1800
+
+# zero-init bss section:
+# clears from _sbss to _ebss
+# _sbss and _ebss are defined by linker script (spiflash.ld)
+     la a0, _sbss
+     la a1, _ebss
+     bge a0, a1, end_init_bss
+loop_init_bss:
+     sw zero, 0(a0)
+     addi a0, a0, 4
+     blt a0, a1, loop_init_bss
+end_init_bss:
+
+# copy data section from SPI Flash to BRAM:
+# copies from _sidata (in flash) to _sdata ... _edata (in BRAM)
+# _sidata, _sdata and _edata are defined by linker script (spiflash.ld)
+     la a0, _sidata
+     la a1, _sdata
+     la a2, _edata
+     bge a1, a2, end_init_data
+loop_init_data:
+     lw a3, 0(a0)
+     sw a3, 0(a1)
+     addi a0, a0, 4
+     addi a1, a1, 4
+     blt a1, a2, loop_init_data
+end_init_data:
+
+     call main
+     ebreak