Constant aw_fel::soc::A10_A13_A20_SRAM_SWAP_BUFFERS

const A10_A13_A20_SRAM_SWAP_BUFFERS: [SRAMSwapBuffers; 3]

Allwinner A10, A13 and A20 SRAM swap buffers.

The FEL code from BROM in A10/A13/A20 sets up two stacks for itself. One at 0x2000 (and growing down) for the IRQ handler. And another one at 0x7000 (and also growing down) for the regular code. In order to use the whole 32 KiB in the A1/A2 sections of SRAM, we need to temporarily move these stacks elsewhere. And the addresses 0x7D00–0x7FFF contain something important too (overwriting them kills FEL). On A10/A13/A20 we can use the SRAM sections A3/A4 (0x8000–0xBFFF) for this purpose.