73 lines
2.3 KiB
C
73 lines
2.3 KiB
C
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#include <stdint.h>
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#include <stddef.h>
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#include "fatfs/ff.h"
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#include "fatfs/sdmmc/sdmmc.h"
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#include "../launcher_path.h"
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void *payload_loc = (void *)0x08000000;
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unsigned int payload_offset = 0x22000;
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unsigned int payload_size = 0x50000;
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// This is where the loader writes the framebuffer offsets
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struct framebuffers {
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uint32_t *top_left;
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uint32_t *top_right;
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uint32_t *bottom;
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} *framebuffers = (struct framebuffers *)0x23FFFE00;
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#define screen_top_width 400
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#define screen_top_height 240
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#define screen_bottom_width 340
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#define screen_bottom_height 240
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#define screen_top_size (screen_top_width * screen_top_height * 3)
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#define screen_bottom_size (screen_bottom_width * screen_bottom_height * 3)
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void memset32(void *dest, uint32_t filler, uint32_t size)
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{
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uint32_t *dest32 = (uint32_t *)dest;
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for (uint32_t i = 0; i < size / 4; i++) {
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dest32[i] = filler;
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}
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}
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void clear_screens() {
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memset32(framebuffers->top_left, 0, screen_top_size);
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memset32(framebuffers->top_right, 0, screen_top_size);
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memset32(framebuffers->bottom, 0, screen_bottom_size);
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}
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// This is supposed to be a small-ish payload that loads a bigger payload.
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// This exists because some payloads are too big to be loaded in the memory of some apps.
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void main()
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{
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FATFS fs;
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FIL handle;
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unsigned int bytes_read;
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// Mount the SD card
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if (f_mount(&fs, "0:", 1) != FR_OK) return;
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// Load the payload
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if (f_open(&handle, "/" LAUNCHER_PATH, FA_READ) != FR_OK) return;
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if (f_lseek(&handle, payload_offset) != FR_OK) return;
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if (f_read(&handle, payload_loc, payload_size, &bytes_read) != FR_OK) return;
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if (f_close(&handle) != FR_OK) return;
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// Unmount the SD card
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if (f_mount(NULL, "0:", 1) != FR_OK) return;
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// This is mostly to adhere to the gateway "standard",
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// so existing gateway payloads don't have to be modified.
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// Write the framebuffer offsets to the places where gateway expects them
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*(uint32_t **)0x080FFFC0 = framebuffers->top_left;
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*(uint32_t **)0x080FFFC4 = framebuffers->top_right;
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*(uint32_t **)0x080FFFD4 = framebuffers->bottom;
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*(uint32_t *)0x080FFFD8 = 0; // Select top framebuffer?
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// Loaded correctly. The rest is up to the payload.
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clear_screens();
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// Jump to the payload, right behind the interrupt vector table.
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((void (*)())(payload_loc + 0x30))();
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}
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