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122 lines
3.0 KiB
122 lines
3.0 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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#ifndef __ASM_ARM_DIV64 |
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#define __ASM_ARM_DIV64 |
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#include <linux/types.h> |
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#include <asm/compiler.h> |
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/* |
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* The semantics of __div64_32() are: |
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* |
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* uint32_t __div64_32(uint64_t *n, uint32_t base) |
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* { |
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* uint32_t remainder = *n % base; |
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* *n = *n / base; |
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* return remainder; |
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* } |
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* |
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* In other words, a 64-bit dividend with a 32-bit divisor producing |
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* a 64-bit result and a 32-bit remainder. To accomplish this optimally |
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* we override the generic version in lib/div64.c to call our __do_div64 |
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* assembly implementation with completely non standard calling convention |
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* for arguments and results (beware). |
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*/ |
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static inline uint32_t __div64_32(uint64_t *n, uint32_t base) |
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{ |
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register unsigned int __base asm("r4") = base; |
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register unsigned long long __n asm("r0") = *n; |
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register unsigned long long __res asm("r2"); |
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unsigned int __rem; |
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asm( __asmeq("%0", "r0") |
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__asmeq("%1", "r2") |
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__asmeq("%2", "r4") |
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"bl __do_div64" |
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: "+r" (__n), "=r" (__res) |
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: "r" (__base) |
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: "ip", "lr", "cc"); |
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__rem = __n >> 32; |
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*n = __res; |
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return __rem; |
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} |
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#define __div64_32 __div64_32 |
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#if !defined(CONFIG_AEABI) |
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/* |
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* In OABI configurations, some uses of the do_div function |
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* cause gcc to run out of registers. To work around that, |
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* we can force the use of the out-of-line version for |
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* configurations that build a OABI kernel. |
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*/ |
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#define do_div(n, base) __div64_32(&(n), base) |
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#else |
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/* |
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* gcc versions earlier than 4.0 are simply too problematic for the |
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* __div64_const32() code in asm-generic/div64.h. First there is |
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* gcc PR 15089 that tend to trig on more complex constructs, spurious |
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* .global __udivsi3 are inserted even if none of those symbols are |
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* referenced in the generated code, and those gcc versions are not able |
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* to do constant propagation on long long values anyway. |
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*/ |
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#define __div64_const32_is_OK (__GNUC__ >= 4) |
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static inline uint64_t __arch_xprod_64(uint64_t m, uint64_t n, bool bias) |
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{ |
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unsigned long long res; |
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register unsigned int tmp asm("ip") = 0; |
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if (!bias) { |
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asm ( "umull %Q0, %R0, %Q1, %Q2\n\t" |
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"mov %Q0, #0" |
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: "=&r" (res) |
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: "r" (m), "r" (n) |
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: "cc"); |
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} else if (!(m & ((1ULL << 63) | (1ULL << 31)))) { |
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res = m; |
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asm ( "umlal %Q0, %R0, %Q1, %Q2\n\t" |
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"mov %Q0, #0" |
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: "+&r" (res) |
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: "r" (m), "r" (n) |
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: "cc"); |
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} else { |
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asm ( "umull %Q0, %R0, %Q2, %Q3\n\t" |
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"cmn %Q0, %Q2\n\t" |
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"adcs %R0, %R0, %R2\n\t" |
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"adc %Q0, %1, #0" |
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: "=&r" (res), "+&r" (tmp) |
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: "r" (m), "r" (n) |
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: "cc"); |
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} |
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if (!(m & ((1ULL << 63) | (1ULL << 31)))) { |
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asm ( "umlal %R0, %Q0, %R1, %Q2\n\t" |
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"umlal %R0, %Q0, %Q1, %R2\n\t" |
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"mov %R0, #0\n\t" |
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"umlal %Q0, %R0, %R1, %R2" |
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: "+&r" (res) |
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: "r" (m), "r" (n) |
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: "cc"); |
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} else { |
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asm ( "umlal %R0, %Q0, %R2, %Q3\n\t" |
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"umlal %R0, %1, %Q2, %R3\n\t" |
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"mov %R0, #0\n\t" |
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"adds %Q0, %1, %Q0\n\t" |
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"adc %R0, %R0, #0\n\t" |
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"umlal %Q0, %R0, %R2, %R3" |
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: "+&r" (res), "+&r" (tmp) |
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: "r" (m), "r" (n) |
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: "cc"); |
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} |
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return res; |
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} |
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#define __arch_xprod_64 __arch_xprod_64 |
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#include <asm-generic/div64.h> |
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#endif |
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#endif
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