71 lines
2.8 KiB
C
71 lines
2.8 KiB
C
/*
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* Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <string.h>
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#include "pico/bootrom.h"
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#include "pico/bootrom/sf_table.h"
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// NOTE THIS FUNCTION TABLE IS NOT PUBLIC OR NECESSARILY COMPLETE...
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// IT IS ***NOT*** SAFE TO CALL THESE FUNCTION POINTERS FROM ARBITRARY CODE
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uint32_t sf_table[SF_TABLE_V2_SIZE / 2];
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void __attribute__((weak)) *sf_clz_func;
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#if !PICO_FLOAT_SUPPORT_ROM_V1
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static __attribute__((noreturn)) void missing_float_func_shim(void) {
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panic("");
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}
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#endif
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void __aeabi_float_init(void) {
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int rom_version = rp2040_rom_version();
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void *rom_table = rom_data_lookup(rom_table_code('S', 'F'));
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#if PICO_FLOAT_SUPPORT_ROM_V1
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if (rom_version == 1) {
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memcpy(&sf_table, rom_table, SF_TABLE_V1_SIZE);
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extern void float_table_shim_on_use_helper(void);
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// todo replace NDEBUG with a more exclusive assertion guard
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#ifndef NDEBUG
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if (*(uint16_t *)0x29ee != 0x0fc4 || // this is packx
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*(uint16_t *)0x29c0 != 0x0dc2 || // this is upackx
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*(uint16_t *)0x2b96 != 0xb5c0 || // this is cordic_vec
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*(uint16_t *)0x2b18 != 0x2500 || // this is packretns
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*(uint16_t *)0x2acc != 0xb510 || // this is float2fix
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*(uint32_t *)0x2cfc != 0x6487ed51 // pi_q29
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) {
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panic("");
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}
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#endif
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// this is a little tricky.. we only want to pull in a shim if the corresponding function
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// is called. to that end we include a SVC instruction with the table offset as the call number
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// followed by the shim function pointer inside the actual wrapper function. that way if the wrapper
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// function is garbage collected, so is the shim function.
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//
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// float_table_shim_on_use_helper expects this SVC instruction in the calling code soon after the address
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// pointed to by IP and patches the float_table entry with the real shim the first time the function is called.
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for(uint i=SF_TABLE_V1_SIZE/4; i<SF_TABLE_V2_SIZE/4; i++) {
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sf_table[i] = (uintptr_t)float_table_shim_on_use_helper;
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}
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// we shim these for -0 and -denormal handling
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sf_table[SF_TABLE_FLOAT2INT/4] = sf_table[SF_TABLE_FLOAT2FIX/4] = (uintptr_t)float_table_shim_on_use_helper;
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}
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#else
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if (rom_version == 1) {
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memcpy(&sf_table, rom_table, SF_TABLE_V1_SIZE);
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// opting for soft failure for now - you'll get a panic at runtime if you call any of the missing methods
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for(uint i=0;i<SF_TABLE_V2_SIZE/4;i++) {
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if (!sf_table[i]) sf_table[i] = (uintptr_t)missing_float_func_shim;
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}
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}
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#endif
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if (rom_version >= 2) {
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assert(*((uint8_t *)(rom_table-2)) * 4 >= SF_TABLE_V2_SIZE);
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memcpy(&sf_table, rom_table, SF_TABLE_V2_SIZE);
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}
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sf_clz_func = rom_func_lookup(rom_table_code('L', '3'));
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}
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