Initial Release

src/rp2_common/pico_mem_ops/CMakeLists.txt

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+if (NOT TARGET pico_mem_ops)
+    #shims for ROM functions for -lgcc functions  (listed below)
+    add_library(pico_mem_ops INTERFACE)
+
+    # no custom implementation; falls thru to compiler
+    add_library(pico_mem_ops_compiler INTERFACE)
+    # PICO_BUILD_DEFINE: PICO_MEM_OPS_COMPILER, whether compiler provided mem_ops memcpy etc. support is being used, type=bool, default=0, but dependent on CMake options, group=pico_mem_ops
+    target_compile_definitions(pico_mem_ops_compiler INTERFACE
+            PICO_MEM_OPS_COMPILER=1
+            )
+
+    # add alias "default" which is just pico.
+    add_library(pico_mem_ops_default INTERFACE)
+    target_link_libraries(pico_mem_ops_default INTERFACE pico_mem_ops_pico)
+
+    set(PICO_DEFAULT_MEM_OPS_IMPL pico_mem_ops_default)
+
+    add_library(pico_mem_ops_pico INTERFACE)
+    target_link_libraries(pico_mem_ops INTERFACE
+            $<IF:$<BOOL:$<TARGET_PROPERTY:PICO_TARGET_MEM_OPS_IMPL>>,$<TARGET_PROPERTY:PICO_TARGET_MEM_OPS_IMPL>,${PICO_DEFAULT_MEM_OPS_IMPL}>)
+
+    # PICO_BUILD_DEFINE: PICO_MEM_OPS_PICO, whether optimized pico/bootrom provided mem_ops memcpy etc. support is being used, type=bool, default=1, but dependent on CMake options, group=pico_mem_ops
+    target_compile_definitions(pico_mem_ops_pico INTERFACE
+            PICO_MEM_OPS_PICO=1
+            )
+
+
+    target_sources(pico_mem_ops_pico INTERFACE
+            ${CMAKE_CURRENT_LIST_DIR}/mem_ops_aeabi.S
+            )
+
+
+    target_link_libraries(pico_mem_ops INTERFACE pico_bootrom)
+
+    pico_wrap_function(pico_mem_ops_pico memcpy)
+    pico_wrap_function(pico_mem_ops_pico memset)
+    pico_wrap_function(pico_mem_ops_pico __aeabi_memcpy)
+    pico_wrap_function(pico_mem_ops_pico __aeabi_memset)
+    pico_wrap_function(pico_mem_ops_pico __aeabi_memcpy4)
+    pico_wrap_function(pico_mem_ops_pico __aeabi_memset4)
+    pico_wrap_function(pico_mem_ops_pico __aeabi_memcpy8)
+    pico_wrap_function(pico_mem_ops_pico __aeabi_memset8)
+
+    macro(pico_set_mem_ops_implementation TARGET IMPL)
+        get_target_property(target_type ${TARGET} TYPE)
+        if ("EXECUTABLE" STREQUAL "${target_type}")
+            set_target_properties(${TARGET} PROPERTIES PICO_TARGET_MEM_OPS_IMPL "pico_mem_ops_${IMPL}")
+        else()
+            message(FATAL_ERROR "mem_ops implementation must be set on executable not library")
+        endif()
+    endmacro()
+endif()

src/rp2_common/pico_mem_ops/include/pico/mem_ops.h

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+/*
+ * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef _PICO_MEMORY_H
+#define _PICO_MEMORY_H
+
+#include "pico/types.h"
+
+/** \file mem_ops.h
+ *  \defgroup pico_mem_ops pico_mem_ops
+ *
+ * Provides optimized replacement implementations of the compiler built-in memcpy, memset and related functions:
+ *
+ * - memset, memcpy
+ * - __aeabi_memset, __aeabi_memset4, __aeabi_memset8, __aeabi_memcpy, __aeabi_memcpy4, __aeabi_memcpy8
+ *
+ * This library does not provide any additional functions
+ */
+#endif

src/rp2_common/pico_mem_ops/mem_ops.c

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+/*
+ * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include "pico/mem_ops.h"

src/rp2_common/pico_mem_ops/mem_ops_aeabi.S

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+/*
+ * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+.syntax unified
+.cpu cortex-m0plus
+.thumb
+
+#include "pico/asm_helper.S"
+
+__pre_init __aeabi_mem_init, 00001
+
+.macro mem_section name
+#if PICO_MEM_IN_RAM
+.section RAM_SECTION_NAME(\name), "ax"
+#else
+.section SECTION_NAME(\name), "ax"
+#endif
+.endm
+
+.equ MEMSET, 0
+.equ MEMCPY, 4
+.equ MEMSET4, 8
+.equ MEMCPY4, 12
+.equ MEM_FUNC_COUNT, 4
+
+# NOTE: All code sections are placed in RAM (at the expense of some veneer cost for calls from flash) because
+#       otherwise code using basic c division operators will require XIP flash access.
+
+.section .data.aeabi_mem_funcs
+.global aeabi_mem_funcs, aeabi_mem_funcs_end
+
+.align 2
+aeabi_mem_funcs:
+    .word rom_table_code('M','S')
+    .word rom_table_code('M','C')
+    .word rom_table_code('S','4')
+    .word rom_table_code('C','4')
+aeabi_mem_funcs_end:
+
+.section .text
+regular_func __aeabi_mem_init
+    ldr r0, =aeabi_mem_funcs
+    movs r1, #MEM_FUNC_COUNT
+    ldr r3, =rom_funcs_lookup
+    bx r3
+
+# lump them both together because likely both to be used, in which case doing so saves 1 word
+# and it only costs 1 word if not
+
+// Note from Run-time ABI for the ARM architecture 4.3.4:
+// If there is an attached device with efficient memory copying or clearing operations
+// (such as a DMA engine), its device supplement specifies whether it may be used in
+// implementations of these functions and what effect such use has on the device’s state.
+
+mem_section aeabi_memset_memcpy
+
+wrapper_func __aeabi_memset
+    // args are backwards
+    eors r0, r1
+    eors r1, r0
+    eors r0, r1
+    ldr r3, =aeabi_mem_funcs
+    ldr r3, [r3, #MEMSET]
+    bx r3
+
+wrapper_func __aeabi_memset4
+wrapper_func __aeabi_memset8
+    // args are backwards
+    eors r0, r1
+    eors r1, r0
+    eors r0, r1
+    ldr r3, =aeabi_mem_funcs
+    ldr r3, [r3, #MEMSET4]
+    bx r3
+
+wrapper_func __aeabi_memcpy4
+wrapper_func __aeabi_memcpy8
+    ldr r3, =aeabi_mem_funcs
+    ldr r3, [r3, #MEMCPY4]
+    bx r3
+
+mem_section memset
+
+wrapper_func memset
+    ldr r3, =aeabi_mem_funcs
+    ldr r3, [r3, #MEMSET]
+    bx r3
+
+mem_section memcpy
+wrapper_func __aeabi_memcpy
+wrapper_func memcpy
+    ldr r3, =aeabi_mem_funcs
+    ldr r3, [r3, #MEMCPY]
+    bx r3
+