API versions

api->version tells the plugin which C8B_API version the running firmware provides. The current version is 7.

Version history

Version	Function pointers	Added
1	36	`alloc`, `free`, `get_free_mem`, `file_open`, `file_read`, `file_write`, `file_seek`, `file_tell`, `file_size`, `file_close`, `get_framebuffer`, `present`, `clear`, `fill_rect`, `get_buttons`, `get_buttons_pressed`, `get_buttons_released`, `get_axis_x`, `get_axis_y`, `audio_queue`, `audio_get_free`, `audio_get_sample_rate`, `get_ticks_ms`, `delay_ms`, `log`, `request_exit`, `exit_requested`, `blit_indexed8`, `profile_begin`, `profile_end`, `profile_report`, `get_axis_rx`, `get_axis_ry`, `file_mkdir`, `file_rename`, `file_remove`
2	51	`get_fast_buffer`, `get_fast_buffer_size`, `invalidate_icache`, `fast_buffer_prefetch`, `fast_buffer_wait`, `fill_rect_blend`, `blit_indexed8_blend`, `alloc_lock`, `alloc_unlock`, `alloc_is_locked`, `alloc_get_used`, `dir_open`, `dir_read`, `dir_close`, `set_working_directory`
3	58	`set_fast_buffer_mode` and `list_entries` (inserted in the middle of the table); `fill_rect_dma`, `get_cycles`, `is_valid_code_ptr`, `get_dep_buffer`, `fast_buffer_prefetch_to`
4	59	`load_itcm_overlay`, constants `C8B_PLUGIN_ITCM_OVERLAY_VMA` / `_SIZE`
5	60	`frame_scratch_prefetch_to`
6	61	`get_depth_strip`
7	64	`present_set_async`, `present_wait`, `bios_debug`

Rebuild v2 plugins. Version 3 inserted set_fast_buffer_mode and list_entries in the middle of the table, which moved every later field. A plugin built against v2 calls the wrong functions for everything after get_fast_buffer_size on v3 or newer firmware.
Since v3, fields are only appended. A plugin built for v3 to v6 runs on v7 firmware. A v7 plugin runs on older v3+ firmware if it checks the version and the pointer before calling newer functions:
```
if (api->version >= 6u && api->get_depth_strip) {
    uint32_t size;
    uint16_t* depth = (uint16_t*)api->get_depth_strip(&size);
}
```
The first 41 fields (version to get_fast_buffer_size) have never moved.
Firmware does not reject plugins by version. The header version field is always 0x00010000; checking api->version is the plugin's job.
Platform-only functions: set_working_directory is NULL on the console and fill_rect_dma is NULL in the emulator. Check these pointers in every version.