diff options
Diffstat (limited to 'nuttx/arch/arm/src/armv7-m/memcpy.S')
| -rw-r--r-- | nuttx/arch/arm/src/armv7-m/memcpy.S | 351 |
1 files changed, 351 insertions, 0 deletions
diff --git a/nuttx/arch/arm/src/armv7-m/memcpy.S b/nuttx/arch/arm/src/armv7-m/memcpy.S new file mode 100644 index 000000000..c6d3ff649 --- /dev/null +++ b/nuttx/arch/arm/src/armv7-m/memcpy.S @@ -0,0 +1,351 @@ +@ +@ armv7m-optimised memcpy, apparently in the public domain +@ +@ Obtained via a posting on the Stellaris forum: +@ http://e2e.ti.com/support/microcontrollers/stellaris_arm_cortex-m3_microcontroller/f/473/t/44360.aspx +@ +@ Posted by rocksoft on Jul 24, 2008 10:19 AM +@ +@ Hi, +@ +@ I recently finished a "memcpy" replacement and thought it might be useful for others... +@ +@ I've put some instructions and the code here: +@ +@ http://www.rock-software.net/downloads/memcpy/ +@ +@ Hope it works for you as well as it did for me. +@ +@ Liam. +@ @ +@ ---------------------------------------------------------------------------- + +.syntax unified + +.thumb + +.cpu cortex-m3 + +@ ---------------------------------------------------------------------------- + + .global memcpy + + +@ ---------------------------------------------------------------------------- +@ Optimised "general" copy routine + +.text + +@ We have 16 possible alignment combinations of src and dst, this jump table directs the copy operation +@ Bits: Src=00, Dst=00 - Long to Long copy +@ Bits: Src=00, Dst=01 - Long to Byte before half word +@ Bits: Src=00, Dst=10 - Long to Half word +@ Bits: Src=00, Dst=11 - Long to Byte before long word +@ Bits: Src=01, Dst=00 - Byte before half word to long +@ Bits: Src=01, Dst=01 - Byte before half word to byte before half word - Same alignment +@ Bits: Src=01, Dst=10 - Byte before half word to half word +@ Bits: Src=01, Dst=11 - Byte before half word to byte before long word +@ Bits: Src=10, Dst=00 - Half word to long word +@ Bits: Src=10, Dst=01 - Half word to byte before half word +@ Bits: Src=10, Dst=10 - Half word to half word - Same Alignment +@ Bits: Src=10, Dst=11 - Half word to byte before long word +@ Bits: Src=11, Dst=00 - Byte before long word to long word +@ Bits: Src=11, Dst=01 - Byte before long word to byte before half word +@ Bits: Src=11, Dst=11 - Byte before long word to half word +@ Bits: Src=11, Dst=11 - Byte before long word to Byte before long word - Same alignment + +MEM_DataCopyTable: + .byte (MEM_DataCopy0 - MEM_DataCopyJump) >> 1 + .byte (MEM_DataCopy1 - MEM_DataCopyJump) >> 1 + .byte (MEM_DataCopy2 - MEM_DataCopyJump) >> 1 + .byte (MEM_DataCopy3 - MEM_DataCopyJump) >> 1 + .byte (MEM_DataCopy4 - MEM_DataCopyJump) >> 1 + .byte (MEM_DataCopy5 - MEM_DataCopyJump) >> 1 + .byte (MEM_DataCopy6 - MEM_DataCopyJump) >> 1 + .byte (MEM_DataCopy7 - MEM_DataCopyJump) >> 1 + .byte (MEM_DataCopy8 - MEM_DataCopyJump) >> 1 + .byte (MEM_DataCopy9 - MEM_DataCopyJump) >> 1 + .byte (MEM_DataCopy10 - MEM_DataCopyJump) >> 1 + .byte (MEM_DataCopy11 - MEM_DataCopyJump) >> 1 + .byte (MEM_DataCopy12 - MEM_DataCopyJump) >> 1 + .byte (MEM_DataCopy13 - MEM_DataCopyJump) >> 1 + .byte (MEM_DataCopy14 - MEM_DataCopyJump) >> 1 + .byte (MEM_DataCopy15 - MEM_DataCopyJump) >> 1 + + .align 2 + +@ ---------------------------------------------------------------------------- + +//#define 10 10 + +MEM_LongCopyTable: + .byte (MEM_LongCopyEnd - MEM_LongCopyJump) >> 1 @ 0 bytes left + .byte 0 @ 4 bytes left + .byte (1 * 10) >> 1 @ 8 bytes left + .byte (2 * 10) >> 1 @ 12 bytes left + .byte (3 * 10) >> 1 @ 16 bytes left + .byte (4 * 10) >> 1 @ 20 bytes left + .byte (5 * 10) >> 1 @ 24 bytes left + .byte (6 * 10) >> 1 @ 28 bytes left + .byte (7 * 10) >> 1 @ 32 bytes left + .byte (8 * 10) >> 1 @ 36 bytes left + + .align 2 + +@ ---------------------------------------------------------------------------- +@ r0 = destination, r1 = source, r2 = length + +.thumb_func + +memcpy: + push {r14} + + @ This allows the inner workings to "assume" a minimum amount of bytes + cmp r2, #4 + blt MEM_DataCopyBytes + + and r14, r0, #3 @ Get destination alignment bits + bfi r14, r1, #2, #2 @ Get source alignment bits + ldr r3, =MEM_DataCopyTable @ Jump table base + tbb [r3, r14] @ Perform jump on src/dst alignment bits +MEM_DataCopyJump: + + .align 4 + +@ ---------------------------------------------------------------------------- +@ Bits: Src=01, Dst=01 - Byte before half word to byte before half word - Same alignment +@ 3 bytes to read for long word aligning + +MEM_DataCopy5: + ldrb r3, [r1], #0x01 + strb r3, [r0], #0x01 + sub r2, r2, #0x01 + +@ ---------------------------------------------------------------------------- +@ Bits: Src=10, Dst=10 - Half word to half word - Same Alignment +@ 2 bytes to read for long word aligning + +MEM_DataCopy10: + ldrb r3, [r1], #0x01 + strb r3, [r0], #0x01 + sub r2, r2, #0x01 + +@ ---------------------------------------------------------------------------- +@ Bits: Src=11, Dst=11 - Byte before long word to Byte before long word - Same alignment +@ 1 bytes to read for long word aligning + +MEM_DataCopy15: + ldrb r3, [r1], #0x01 + strb r3, [r0], #0x01 + sub r2, r2, #0x01 + +@ ---------------------------------------------------------------------------- +@ Bits: Src=00, Dst=00 - Long to Long copy + +MEM_DataCopy0: + @ Save regs + push {r4-r12} + + cmp r2, #0x28 + blt MEM_DataCopy0_2 + +MEM_DataCopy0_1: + ldmia r1!, {r3-r12} + stmia r0!, {r3-r12} + sub r2, r2, #0x28 + cmp r2, #0x28 + bge MEM_DataCopy0_1 + +MEM_DataCopy0_2: + @ Copy remaining long words + ldr r14, =MEM_LongCopyTable + lsr r11, r2, #0x02 + tbb [r14, r11] + +MEM_LongCopyJump: + ldr.w r3, [r1], #0x04 @ 4 bytes remain + str.w r3, [r0], #0x04 + b MEM_LongCopyEnd + ldmia.w r1!, {r3-r4} @ 8 bytes remain + stmia.w r0!, {r3-r4} + b MEM_LongCopyEnd + ldmia.w r1!, {r3-r5} @ 12 bytes remain + stmia.w r0!, {r3-r5} + b MEM_LongCopyEnd + ldmia.w r1!, {r3-r6} @ 16 bytes remain + stmia.w r0!, {r3-r6} + b MEM_LongCopyEnd + ldmia.w r1!, {r3-r7} @ 20 bytes remain + stmia.w r0!, {r3-r7} + b MEM_LongCopyEnd + ldmia.w r1!, {r3-r8} @ 24 bytes remain + stmia.w r0!, {r3-r8} + b MEM_LongCopyEnd + ldmia.w r1!, {r3-r9} @ 28 bytes remain + stmia.w r0!, {r3-r9} + b MEM_LongCopyEnd + ldmia.w r1!, {r3-r10} @ 32 bytes remain + stmia.w r0!, {r3-r10} + b MEM_LongCopyEnd + ldmia.w r1!, {r3-r11} @ 36 bytes remain + stmia.w r0!, {r3-r11} + +MEM_LongCopyEnd: + pop {r4-r12} + and r2, r2, #0x03 @ All the longs have been copied + +@ ---------------------------------------------------------------------------- + +MEM_DataCopyBytes: + @ Deal with up to 3 remaining bytes + cmp r2, #0x00 + it eq + popeq {pc} + ldrb r3, [r1], #0x01 + strb r3, [r0], #0x01 + subs r2, r2, #0x01 + it eq + popeq {pc} + ldrb r3, [r1], #0x01 + strb r3, [r0], #0x01 + subs r2, r2, #0x01 + it eq + popeq {pc} + ldrb r3, [r1], #0x01 + strb r3, [r0], #0x01 + pop {pc} + + .align 4 + +@ ---------------------------------------------------------------------------- +@ Bits: Src=01, Dst=11 - Byte before half word to byte before long word +@ 3 bytes to read for long word aligning the source + +MEM_DataCopy7: + ldrb r3, [r1], #0x01 + strb r3, [r0], #0x01 + sub r2, r2, #0x01 + +@ ---------------------------------------------------------------------------- +@ Bits: Src=10, Dst=00 - Half word to long word +@ 2 bytes to read for long word aligning the source + +MEM_DataCopy8: + ldrb r3, [r1], #0x01 + strb r3, [r0], #0x01 + sub r2, r2, #0x01 + +@ ---------------------------------------------------------------------------- +@ Bits: Src=11, Dst=01 - Byte before long word to byte before half word +@ 1 byte to read for long word aligning the source + +MEM_DataCopy13: + ldrb r3, [r1], #0x01 + strb r3, [r0], #0x01 + sub r2, r2, #0x01 + +@ ---------------------------------------------------------------------------- +@ Bits: Src=00, Dst=10 - Long to Half word + +MEM_DataCopy2: + cmp r2, #0x28 + blt MEM_DataCopy2_1 + + @ Save regs + push {r4-r12} +MEM_DataCopy2_2: + ldmia r1!, {r3-r12} + + strh r3, [r0], #0x02 + + lsr r3, r3, #0x10 + bfi r3, r4, #0x10, #0x10 + lsr r4, r4, #0x10 + bfi r4, r5, #0x10, #0x10 + lsr r5, r5, #0x10 + bfi r5, r6, #0x10, #0x10 + lsr r6, r6, #0x10 + bfi r6, r7, #0x10, #0x10 + lsr r7, r7, #0x10 + bfi r7, r8, #0x10, #0x10 + lsr r8, r8, #0x10 + bfi r8, r9, #0x10, #0x10 + lsr r9, r9, #0x10 + bfi r9, r10, #0x10, #0x10 + lsr r10, r10, #0x10 + bfi r10, r11, #0x10, #0x10 + lsr r11, r11, #0x10 + bfi r11, r12, #0x10, #0x10 + stmia r0!, {r3-r11} + lsr r12, r12, #0x10 + strh r12, [r0], #0x02 + + sub r2, r2, #0x28 + cmp r2, #0x28 + bge MEM_DataCopy2_2 + pop {r4-r12} + +MEM_DataCopy2_1: @ Read longs and write 2 x half words + cmp r2, #4 + blt MEM_DataCopyBytes + ldr r3, [r1], #0x04 + strh r3, [r0], #0x02 + lsr r3, r3, #0x10 + strh r3, [r0], #0x02 + sub r2, r2, #0x04 + b MEM_DataCopy2 + +@ ---------------------------------------------------------------------------- +@ Bits: Src=01, Dst=00 - Byte before half word to long +@ Bits: Src=01, Dst=10 - Byte before half word to half word +@ 3 bytes to read for long word aligning the source + +MEM_DataCopy4: +MEM_DataCopy6: + @ Read B and write B + ldrb r3, [r1], #0x01 + strb r3, [r0], #0x01 + sub r2, r2, #0x01 + +@ ---------------------------------------------------------------------------- +@ Bits: Src=10, Dst=01 - Half word to byte before half word +@ Bits: Src=10, Dst=11 - Half word to byte before long word +@ 2 bytes to read for long word aligning the source + +MEM_DataCopy9: +MEM_DataCopy11: + ldrb r3, [r1], #0x01 + strb r3, [r0], #0x01 + sub r2, r2, #0x01 + +@ ---------------------------------------------------------------------------- +@ Bits: Src=11, Dst=00 - Byte before long word to long word +@ Bits: Src=11, Dst=11 - Byte before long word to half word +@ 1 byte to read for long word aligning the source + +MEM_DataCopy12: +MEM_DataCopy14: + @ Read B and write B + ldrb r3, [r1], #0x01 + strb r3, [r0], #0x01 + sub r2, r2, #0x01 + +@ ---------------------------------------------------------------------------- +@ Bits: Src=00, Dst=01 - Long to Byte before half word +@ Bits: Src=00, Dst=11 - Long to Byte before long word + +MEM_DataCopy1: @ Read longs, write B->H->B +MEM_DataCopy3: + cmp r2, #4 + blt MEM_DataCopyBytes + ldr r3, [r1], #0x04 + strb r3, [r0], #0x01 + lsr r3, r3, #0x08 + strh r3, [r0], #0x02 + lsr r3, r3, #0x10 + strb r3, [r0], #0x01 + sub r2, r2, #0x04 + b MEM_DataCopy3 + +@ ---------------------------------------------------------------------------- + |