Initial Release

src/rp2_common/pico_bit_ops/CMakeLists.txt

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+if (NOT TARGET pico_bit_ops)
+    #shims for ROM functions for -lgcc functions  (listed below)
+    add_library(pico_bit_ops INTERFACE)
+
+    # no custom implementation; falls thru to compiler
+    add_library(pico_bit_ops_compiler INTERFACE)
+    # PICO_BUILD_DEFINE: PICO_BIT_OPS_COMPILER, whether compiler provided bit_ops bit functions support is being used, type=bool, default=0, but dependent on CMake options, group=pico_bit_ops
+    target_compile_definitions(pico_bit_ops_compiler INTERFACE
+            PICO_BIT_OPS_COMPILER=1
+            )
+
+    # add alias "default" which is just pico.
+    add_library(pico_bit_ops_default INTERFACE)
+    target_link_libraries(pico_bit_ops_default INTERFACE pico_bit_ops_pico)
+
+    set(PICO_DEFAULT_BIT_OPS_IMPL pico_bit_ops_default)
+
+    add_library(pico_bit_ops_pico INTERFACE)
+    target_link_libraries(pico_bit_ops INTERFACE
+            $<IF:$<BOOL:$<TARGET_PROPERTY:PICO_TARGET_BIT_OPS_IMPL>>,$<TARGET_PROPERTY:PICO_TARGET_BIT_OPS_IMPL>,${PICO_DEFAULT_BIT_OPS_IMPL}>)
+
+    # PICO_BUILD_DEFINE: PICO_BIT_OPS_PICO, whether optimized pico/bootrom provided bit_ops bit functions support is being used, type=bool, default=1, but dependent on CMake options, group=pico_bit_ops
+    target_compile_definitions(pico_bit_ops_pico INTERFACE
+            PICO_BIT_OPS_PICO=1
+            )
+
+    target_sources(pico_bit_ops_pico INTERFACE
+            ${CMAKE_CURRENT_LIST_DIR}/bit_ops_aeabi.S
+            )
+
+    target_link_libraries(pico_bit_ops_pico INTERFACE pico_bootrom pico_bit_ops_headers)
+
+    # gcc
+    pico_wrap_function(pico_bit_ops_pico __clzsi2)
+    pico_wrap_function(pico_bit_ops_pico __clzsi2)
+    pico_wrap_function(pico_bit_ops_pico __clzdi2)
+    pico_wrap_function(pico_bit_ops_pico __ctzsi2)
+    pico_wrap_function(pico_bit_ops_pico __ctzdi2)
+    pico_wrap_function(pico_bit_ops_pico __popcountsi2)
+    pico_wrap_function(pico_bit_ops_pico __popcountdi2)
+
+    # armclang
+    pico_wrap_function(pico_bit_ops_pico __clz)
+    pico_wrap_function(pico_bit_ops_pico __clzl)
+    pico_wrap_function(pico_bit_ops_pico __clzsi2)
+    pico_wrap_function(pico_bit_ops_pico __clzll)
+
+    macro(pico_set_bit_ops_implementation TARGET IMPL)
+        get_target_property(target_type ${TARGET} TYPE)
+        if ("EXECUTABLE" STREQUAL "${target_type}")
+            set_target_properties(${TARGET} PROPERTIES PICO_TARGET_BIT_OPS_IMPL "pico_bit_ops_${IMPL}")
+        else()
+            message(FATAL_ERROR "bit_ops implementation must be set on executable not library")
+        endif()
+    endmacro()
+    
+endif()

src/rp2_common/pico_bit_ops/bit_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_bits_init, 00010
+
+.macro bits_section name
+#if PICO_BITS_IN_RAM
+.section RAM_SECTION_NAME(\name), "ax"
+#else
+.section SECTION_NAME(\name), "ax"
+#endif
+.endm
+
+.section .data.aeabi_bits_funcs
+.global aeabi_bits_funcs, aeabi_bits_funcs_end
+.equ BITS_FUNC_COUNT, 4
+.align 4
+aeabi_bits_funcs:
+    .word rom_table_code('P','3') // popcount32
+    .word rom_table_code('L','3') // clz32
+    .word rom_table_code('T','3') // ctz32
+    .word rom_table_code('R','3') // reverse32
+aeabi_bits_funcs_end:
+
+.section .text
+.thumb_func
+__aeabi_bits_init:
+    ldr r0, =aeabi_bits_funcs
+    movs r1, #BITS_FUNC_COUNT
+    ldr r3, =rom_funcs_lookup
+    bx r3
+
+.equ POPCOUNT32, 0
+.equ CLZ32, 4
+.equ CTZ32, 8
+.equ REVERSE32, 12
+
+bits_section clzsi
+wrapper_func __clz
+wrapper_func __clzl
+wrapper_func __clzsi2
+    ldr r3, =aeabi_bits_funcs
+    ldr r3, [r3, #CLZ32]
+    bx r3
+
+bits_section ctzsi
+wrapper_func __ctzsi2
+    ldr r3, =aeabi_bits_funcs
+    ldr r3, [r3, #CTZ32]
+    bx r3
+
+bits_section popcountsi
+wrapper_func __popcountsi2
+    ldr r3, =aeabi_bits_funcs
+    ldr r3, [r3, #POPCOUNT32]
+    bx r3
+
+bits_section clzdi
+wrapper_func __clzll
+wrapper_func __clzdi2
+    ldr r3, =aeabi_bits_funcs
+    ldr r3, [r3, #CLZ32]
+    cmp r1, #0
+    bne 1f
+    push {lr}
+    blx r3
+    adds r0, #32
+    pop {pc}
+1:
+    mov r0, r1
+    bx r3
+
+bits_section ctzdi
+wrapper_func __ctzdi2
+    ldr r3, =aeabi_bits_funcs
+    ldr r3, [r3, #CTZ32]
+    cmp r0, #0
+    bne 1f
+    bx r3
+1:
+    push {lr}
+    mov r0, r1
+    blx r3
+    adds r0, #32
+    pop {pc}
+
+bits_section popcountdi
+wrapper_func __popcountdi2
+    ldr r3, =aeabi_bits_funcs
+    ldr r3, [r3, #POPCOUNT32]
+    push {r1, r3, lr}
+    blx r3
+    mov ip, r0
+    pop {r0, r3}
+    blx r3
+    mov r1, ip
+    add r0, r1
+    pop {pc}
+
+bits_section reverse32
+regular_func reverse32
+    ldr r3, =aeabi_bits_funcs
+    ldr r3, [r3, #REVERSE32]
+    bx r3
+
+bits_section __rev
+regular_func __rev
+regular_func __revl
+    ldr r3, =aeabi_bits_funcs
+    ldr r3, [r3, #REVERSE32]
+    bx r3
+
+bits_section __revll
+regular_func __revll
+    push {lr}
+    ldr r3, =aeabi_bits_funcs
+    ldr r3, [r3, #REVERSE32]
+    push {r1, r3}
+    blx r3
+    mov ip, r0 // reverse32 preserves ip
+    pop {r0, r3}
+    blx r3
+    mov r1, ip
+    pop {pc}