Revert "adler32: Drop SSE3 support"

This reverts commit ba327e76c5b110044ec8ebb75630e79506dfbed8 and re-adds
SSE3 support at the request of Noisytoot.

3 files changed, 232 insertions, 4 deletions

diff --git a/internal/adler32/adler32_amd64.go b/internal/adler32/adler32_amd64.go
index 3fbcb4d8..88a854ed 100644
--- a/internal/adler32/adler32_amd64.go
+++ b/internal/adler32/adler32_amd64.go
@@ -15,6 +15,7 @@ import (
 const Size = 4
 
 var (
+	hasSSE3 = cpu.X86.HasSSE3
 	hasAVX2 = cpu.X86.HasAVX2
 )
 
@@ -26,7 +27,7 @@ func (d *digest) Reset() { *d = 1 }
 
 // New returns a new hash.Hash32 computing the Adler-32 checksum.
 func New() hash.Hash32 {
-	if !hasAVX2 {
+	if !hasSSE3 {
 		return adler32.New()
 	}
 	d := new(digest)
@@ -59,7 +60,11 @@ func (d *digest) BlockSize() int { return 4 }
 func (d *digest) Write(data []byte) (nn int, err error) {
 	if len(data) >= 64 {
 		var h uint32
-		h = adler32_avx2(uint32(*d), data)
+		if hasAVX2 {
+			h = adler32_avx2(uint32(*d), data)
+		} else {
+			h = adler32_sse3(uint32(*d), data)
+		}
 		*d = digest(h)
 	} else {
 		h := update(uint32(*d), data)
@@ -77,9 +82,12 @@ func (d *digest) Sum(in []byte) []byte {
 
 // Checksum returns the Adler-32 checksum of data.
 func Checksum(data []byte) uint32 {
-	if !hasAVX2 || len(data) < 64 {
+	if !hasSSE3 || len(data) < 64 {
 		return update(1, data)
 	}
 
-	return adler32_avx2(1, data)
+	if hasAVX2 {
+		return adler32_avx2(1, data)
+	}
+	return adler32_sse3(1, data)
 }
diff --git a/internal/adler32/adler32_sse3.go b/internal/adler32/adler32_sse3.go
new file mode 100644
index 00000000..8e8c8a9b
--- /dev/null
+++ b/internal/adler32/adler32_sse3.go
@@ -0,0 +1,6 @@
+//go:build !purego && amd64
+
+package adler32
+
+//go:noescape
+func adler32_sse3(in uint32, buf []byte) uint32
diff --git a/internal/adler32/adler32_sse3.s b/internal/adler32/adler32_sse3.s
new file mode 100644
index 00000000..5880bab8
--- /dev/null
+++ b/internal/adler32/adler32_sse3.s
@@ -0,0 +1,214 @@
+//go:build !purego && amd64
+
+#include "textflag.h"
+
+DATA weights_17_32<>+0x00(SB)/8, $0x191a1b1c1d1e1f20
+DATA weights_17_32<>+0x08(SB)/8, $0x1112131415161718
+GLOBL weights_17_32<>(SB), (RODATA|NOPTR), $16
+
+DATA ones_u16<>+0x00(SB)/8, $0x0001000100010001
+DATA ones_u16<>+0x08(SB)/8, $0x0001000100010001
+GLOBL ones_u16<>(SB), (RODATA|NOPTR), $16
+
+DATA weights_1_16<>+0x00(SB)/8, $0x090a0b0c0d0e0f10
+DATA weights_1_16<>+0x08(SB)/8, $0x0102030405060708
+GLOBL weights_1_16<>(SB), (RODATA|NOPTR), $16
+
+TEXT ·adler32_sse3(SB), NOSPLIT, $0-36
+	MOVLQZX in+0(FP), DI
+	MOVQ    buf_base+8(FP), SI
+	MOVQ    buf_len+16(FP), DX
+	MOVQ    buf_cap+24(FP), CX
+	NOP
+	NOP
+	NOP
+	WORD    $0xf889
+	LONG    $0xc8b70f44
+	WORD    $0xe8c1; BYTE $0x10
+	WORD    $0xd189
+	WORD    $0xe183; BYTE $0x1f
+	CMPQ    DX, $0x20
+	JAE     block_loop_setup
+	WORD    $0x8944; BYTE $0xcf
+	JMP     tail_entry
+
+block_loop_setup:
+	SHRQ $0x5, DX
+	LONG $0xc0ef0f66
+	MOVO weights_17_32<>(SB), X1
+	MOVO ones_u16<>(SB), X2
+	MOVO weights_1_16<>(SB), X3
+	LONG $0x8071b841; WORD $0x8007
+
+block_outer_loop:
+	CMPQ DX, $0xad
+	LONG $0x00adba41; WORD $0x0000
+	LONG $0xd2420f4c
+	WORD $0x8944; BYTE $0xcf
+	LONG $0xfaaf0f41
+	LONG $0xef6e0f66
+	LONG $0xe06e0f66
+	WORD $0x8944; BYTE $0xd0
+	LONG $0xf6ef0f66
+
+block_inner_loop:
+	LONG  $0x3e6f0ff3
+	LONG  $0x6f0f4466; BYTE $0xc7
+	LONG  $0x04380f66; BYTE $0xf9
+	LONG  $0xfaf50f66
+	LONG  $0xfcfe0f66
+	LONG  $0x666f0ff3; BYTE $0x10
+	LONG  $0xeefe0f66
+	LONG  $0xf60f4466; BYTE $0xc0
+	LONG  $0xfe0f4466; BYTE $0xc6
+	LONG  $0xf46f0f66
+	LONG  $0xf0f60f66
+	LONG  $0xfe0f4166; BYTE $0xf0
+	LONG  $0x04380f66; BYTE $0xe3
+	LONG  $0xe2f50f66
+	LONG  $0xe7fe0f66
+	ADDQ  $0x20, SI
+	WORD  $0xc8ff
+	JNE   block_inner_loop
+	LONG  $0xf5720f66; BYTE $0x05
+	LONG  $0xe5fe0f66
+	LONG  $0xee700f66; BYTE $0xb1
+	LONG  $0xeefe0f66
+	LONG  $0xf5700f66; BYTE $0xee
+	LONG  $0xf5fe0f66
+	LONG  $0xf77e0f66
+	WORD  $0x0144; BYTE $0xcf
+	LONG  $0xec700f66; BYTE $0xb1
+	LONG  $0xecfe0f66
+	LONG  $0xe5700f66; BYTE $0xee
+	LONG  $0xe5fe0f66
+	LONG  $0xe07e0f66
+	MOVQ  DI, R9
+	IMULQ R8, R9
+	SHRQ  $0x2f, R9
+	LONG  $0xf1c96945; WORD $0x00ff; BYTE $0x00
+	WORD  $0x2944; BYTE $0xcf
+	MOVQ  AX, R9
+	IMULQ R8, R9
+	SHRQ  $0x2f, R9
+	LONG  $0xf1c96945; WORD $0x00ff; BYTE $0x00
+	WORD  $0x2944; BYTE $0xc8
+	WORD  $0x8941; BYTE $0xf9
+	SUBQ  R10, DX
+	JNE   block_outer_loop
+
+tail_entry:
+	WORD $0x8548; BYTE $0xc9
+	JE   return_result
+	CMPL CX, $0x10
+	JB   tail_bytes_setup
+	WORD $0xb60f; BYTE $0x16
+	WORD $0xd701
+	WORD $0xf801
+	LONG $0x0156b60f
+	WORD $0xfa01
+	WORD $0xd001
+	LONG $0x027eb60f
+	WORD $0xd701
+	WORD $0xf801
+	LONG $0x0356b60f
+	WORD $0xfa01
+	WORD $0xd001
+	LONG $0x047eb60f
+	WORD $0xd701
+	WORD $0xf801
+	LONG $0x0556b60f
+	WORD $0xfa01
+	WORD $0xd001
+	LONG $0x067eb60f
+	WORD $0xd701
+	WORD $0xf801
+	LONG $0x0756b60f
+	WORD $0xfa01
+	WORD $0xd001
+	LONG $0x087eb60f
+	WORD $0xd701
+	WORD $0xf801
+	LONG $0x0956b60f
+	WORD $0xfa01
+	WORD $0xd001
+	LONG $0x0a7eb60f
+	WORD $0xd701
+	WORD $0xf801
+	LONG $0x0b56b60f
+	WORD $0xfa01
+	WORD $0xd001
+	LONG $0x0c7eb60f
+	WORD $0xd701
+	WORD $0xf801
+	LONG $0x0d56b60f
+	WORD $0xfa01
+	WORD $0xd001
+	LONG $0x46b60f44; BYTE $0x0e
+	WORD $0x0141; BYTE $0xd0
+	WORD $0x0144; BYTE $0xc0
+	LONG $0x0f7eb60f
+	WORD $0x0144; BYTE $0xc7
+	WORD $0xf801
+	ADDQ $-0x10, CX
+	JE   final_reduce
+	ADDQ $0x10, SI
+
+tail_bytes_setup:
+	LEAQ -0x1(CX), DX
+	MOVQ CX, R9
+	ANDQ $0x3, R9
+	JE   tail_dword_setup
+	XORL R8, R8
+
+tail_byte_loop:
+	LONG $0x14b60f46; BYTE $0x06
+	WORD $0x0144; BYTE $0xd7
+	WORD $0xf801
+	INCQ R8
+	CMPQ R9, R8
+	JNE  tail_byte_loop
+	ADDQ R8, SI
+	SUBQ R8, CX
+
+tail_dword_setup:
+	CMPQ DX, $0x3
+	JB   final_reduce
+	XORL DX, DX
+
+tail_dword_loop:
+	LONG $0x04b60f44; BYTE $0x16
+	WORD $0x0141; BYTE $0xf8
+	WORD $0x0144; BYTE $0xc0
+	LONG $0x167cb60f; BYTE $0x01
+	WORD $0x0144; BYTE $0xc7
+	WORD $0xf801
+	LONG $0x44b60f44; WORD $0x0216
+	WORD $0x0141; BYTE $0xf8
+	WORD $0x0144; BYTE $0xc0
+	LONG $0x167cb60f; BYTE $0x03
+	WORD $0x0144; BYTE $0xc7
+	WORD $0xf801
+	ADDQ $0x4, DX
+	CMPQ CX, DX
+	JNE  tail_dword_loop
+
+final_reduce:
+	LONG  $0x000f8f8d; WORD $0xffff
+	CMPL  DI, $0xfff1
+	WORD  $0x420f; BYTE $0xcf
+	WORD  $0xc289
+	LONG  $0x078071be; BYTE $0x80
+	IMULQ DX, SI
+	SHRQ  $0x2f, SI
+	LONG  $0xfff1d669; WORD $0x0000
+	WORD  $0xd029
+	WORD  $0xcf89
+
+return_result:
+	WORD $0xe0c1; BYTE $0x10
+	WORD $0xf809
+	NOP
+	NOP
+	MOVL AX, ret+32(FP)
+	RET