add PICO_DIVIDER_DISABLE_INTERRUPTS flag which makes PICO_DIVIDER disable interrupts around division rather than using co-operative guards to protect nested use (i.e. within IRQ/exception). Use of this flag can simplify porting of RTOSes but with a different performance profile (#372)
This commit is contained in:
Graham Sanderson
GitHub
@ -11,16 +11,21 @@
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.cpu cortex-m0plus
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.thumb
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// PICO_CONFIG: PICO_DIVIDER_DISABLE_INTERRUPTS, Disable interrupts around division such that divider state need not be saved/restored in exception handlers, default=0, group=pico_divider
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#include "pico/asm_helper.S"
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// PICO_CONFIG: PICO_DIVIDER_CALL_IDIV0, Whether 32 bit division by zero should call __aeabi_idiv0, default=1, group=pico_divider
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#ifndef PICO_DIVIDER_CALL_IDIV0
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#define PICO_DIVIDER_CALL_IDIV0 1
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#endif
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// PICO_CONFIG: PICO_DIVIDER_CALL_IDIV0, Whether 64 bit division by zero should call __aeabi_ldiv0, default=1, group=pico_divider
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#ifndef PICO_DIVIDER_CALL_LDIV0
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#define PICO_DIVIDER_CALL_LDIV0 1
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#endif
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// PICO_CONFIG: PICO_DIVIDER_IN_RAM, Whether divider functions should be placed in RAM, default=0, group=pico_divider
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.macro div_section name
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#if PICO_DIVIDER_IN_RAM
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.section RAM_SECTION_NAME(\name), "ax"
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@ -56,6 +61,8 @@ need to change SHIFT above
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#error register layout has changed - we rely on this order to make sure we save/restore in the right order
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#endif
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#if !PICO_DIVIDER_DISABLE_INTERRUPTS
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# SIO_BASE ptr in r2
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.macro save_div_state_and_lr
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ldr r3, [r2, #SIO_DIV_CSR_OFFSET]
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@ -137,6 +144,7 @@ need to change SHIFT above
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pop {r4, r5, r6, r7, pc}
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.endm
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#endif /* !PICO_DIVIDER_DISABLE_INTERRUPTS */
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// since idiv and idivmod only differ by a cycle, we'll make them the same!
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div_section WRAPPER_FUNC_NAME(__aeabi_idiv)
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@ -145,12 +153,22 @@ wrapper_func __aeabi_idiv
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wrapper_func __aeabi_idivmod
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regular_func div_s32s32
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regular_func divmod_s32s32
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#if !PICO_DIVIDER_DISABLE_INTERRUPTS
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ldr r2, =(SIO_BASE)
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# to support IRQ usage we must save/restore
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ldr r3, [r2, #SIO_DIV_CSR_OFFSET]
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lsrs r3, #SIO_DIV_CSR_DIRTY_SHIFT_FOR_CARRY
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bcs divmod_s32s32_savestate
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regular_func divmod_s32s32_unsafe
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#else
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# to avoid too much source code spaghetti with restoring interrupts, we make this the same as the other funcs
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# in the PICO_DIVIDER_DISABLE_INTERRUPTS case; i.e. it is not a faster function; this seems reasonable as there
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# are the hardware_divider functions that can be used instead anyway
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regular_func divmod_s32s32_unsafe
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ldr r2, =(SIO_BASE)
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mrs r3, PRIMASK
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cpsid i
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#endif /* !PICO_DIVIDER_DISABLE_INTERRUPTS */
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str r0, [r2, #SIO_DIV_SDIVIDEND_OFFSET]
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str r1, [r2, #SIO_DIV_SDIVISOR_OFFSET]
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cmp r1, #0
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@ -159,8 +177,14 @@ regular_func divmod_s32s32_unsafe
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// return 64 bit value so we can efficiently return both (note read order is important since QUOTIENT must be read last)
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ldr r1, [r2, #SIO_DIV_REMAINDER_OFFSET]
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ldr r0, [r2, #SIO_DIV_QUOTIENT_OFFSET]
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#if PICO_DIVIDER_DISABLE_INTERRUPTS
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msr PRIMASK, r3
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#endif /* PICO_DIVIDER_DISABLE_INTERRUPTS */
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bx lr
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1:
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#if PICO_DIVIDER_DISABLE_INTERRUPTS
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msr PRIMASK, r3
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#endif /* PICO_DIVIDER_DISABLE_INTERRUPTS */
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push {r2, lr}
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movs r1, #0x80
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lsls r1, #24
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@ -176,11 +200,13 @@ regular_func divmod_s32s32_unsafe
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movs r1, #0 // remainder 0
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// need to restore saved r2 as it hold SIO ptr
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pop {r2, pc}
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#if !PICO_DIVIDER_DISABLE_INTERRUPTS
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.align 2
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regular_func divmod_s32s32_savestate
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save_div_state_and_lr
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bl divmod_s32s32_unsafe
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restore_div_state_and_return
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#endif /* !PICO_DIVIDER_DISABLE_INTERRUPTS */
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// since uidiv and uidivmod only differ by a cycle, we'll make them the same!
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div_section WRAPPER_FUNC_NAME(__aeabi_uidiv)
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@ -188,12 +214,22 @@ regular_func div_u32u32
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regular_func divmod_u32u32
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wrapper_func __aeabi_uidiv
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wrapper_func __aeabi_uidivmod
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#if !PICO_DIVIDER_DISABLE_INTERRUPTS
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ldr r2, =(SIO_BASE)
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# to support IRQ usage we must save/restore
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ldr r3, [r2, #SIO_DIV_CSR_OFFSET]
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lsrs r3, #SIO_DIV_CSR_DIRTY_SHIFT_FOR_CARRY
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bcs divmod_u32u32_savestate
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regular_func divmod_u32u32_unsafe
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#else
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# to avoid too much source code spaghetti with restoring interrupts, we make this the same as the other funcs
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# in the PICO_DIVIDER_DISABLE_INTERRUPTS case; i.e. it is not a faster function; this seems reasonable as there
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# are the hardware_divider functions that can be used instead anyway
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regular_func divmod_u32u32_unsafe
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ldr r2, =(SIO_BASE)
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mrs r3, PRIMASK
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cpsid i
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#endif /* !PICO_DIVIDER_DISABLE_INTERRUPTS */
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str r0, [r2, #SIO_DIV_UDIVIDEND_OFFSET]
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str r1, [r2, #SIO_DIV_UDIVISOR_OFFSET]
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cmp r1, #0
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@ -202,8 +238,14 @@ regular_func divmod_u32u32_unsafe
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// return 64 bit value so we can efficiently return both (note read order is important since QUOTIENT must be read last)
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ldr r1, [r2, #SIO_DIV_REMAINDER_OFFSET]
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ldr r0, [r2, #SIO_DIV_QUOTIENT_OFFSET]
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#if PICO_DIVIDER_DISABLE_INTERRUPTS
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msr PRIMASK, r3
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#endif /* PICO_DIVIDER_DISABLE_INTERRUPTS */
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bx lr
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1:
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#if PICO_DIVIDER_DISABLE_INTERRUPTS
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msr PRIMASK, r3
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#endif /* PICO_DIVIDER_DISABLE_INTERRUPTS */
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push {r2, lr}
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cmp r0, #0
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beq 1f
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@ -216,11 +258,13 @@ regular_func divmod_u32u32_unsafe
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movs r1, #0 // remainder 0
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// need to restore saved r2 as it hold SIO ptr
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pop {r2, pc}
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#if !PICO_DIVIDER_DISABLE_INTERRUPTS
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.align 2
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regular_func divmod_u32u32_savestate
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save_div_state_and_lr
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bl divmod_u32u32_unsafe
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restore_div_state_and_return
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#endif /* !PICO_DIVIDER_DISABLE_INTERRUPTS */
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div_section WRAPPER_FUNC_NAME(__aeabi_ldiv)
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@ -228,6 +272,7 @@ div_section WRAPPER_FUNC_NAME(__aeabi_ldiv)
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wrapper_func __aeabi_ldivmod
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regular_func div_s64s64
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regular_func divmod_s64s64
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#if !PICO_DIVIDER_DISABLE_INTERRUPTS
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mov ip, r2
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ldr r2, =(SIO_BASE)
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# to support IRQ usage we must save/restore
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@ -241,11 +286,20 @@ divmod_s64s64_savestate:
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save_div_state_and_lr_64
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bl divmod_s64s64_unsafe
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restore_div_state_and_return_64
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#else
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push {r4, lr}
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mrs r4, PRIMASK
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cpsid i
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bl divmod_s64s64_unsafe
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msr PRIMASK, r4
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pop {r4, pc}
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#endif /* !PICO_DIVIDER_DISABLE_INTERRUPTS */
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.align 2
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wrapper_func __aeabi_uldivmod
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regular_func div_u64u64
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regular_func divmod_u64u64
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#if !PICO_DIVIDER_DISABLE_INTERRUPTS
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mov ip, r2
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ldr r2, =(SIO_BASE)
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# to support IRQ usage we must save/restore
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@ -259,6 +313,15 @@ regular_func divmod_u64u64_savestate
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save_div_state_and_lr_64
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bl divmod_u64u64_unsafe
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restore_div_state_and_return_64
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#else
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push {r4, lr}
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mrs r4, PRIMASK
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cpsid i
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bl divmod_u64u64_unsafe
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msr PRIMASK, r4
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pop {r4, pc}
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#endif /* !PICO_DIVIDER_DISABLE_INTERRUPTS */
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.macro dneg lo,hi
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mvns \hi,\hi
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rsbs \lo,#0
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