init: 自 zomaintain/backend/rdplib 平移独立成库; module path 从上游 github.com/nakagami/grdp 改为 git.zeroonesoft.cn/golib/rdplib

2026-09-19 18:55:43 +08:00
commit 1096fbce9d
94 changed files with 36790 additions and 0 deletions
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+// Scalar ARM64 implementation of ycoCgToBGRANEON.
+// Processes one pixel per iteration (no chroma subsampling, alpha = 0xFF).
+// Go arm64 assembler lacks SSHR (signed vector shift right), SSHL (by register),
+// and SQXTUN (saturating narrow), so we use scalar GP instructions instead.
+// Stack ABI (ABI0):
+//   pixels+0(FP)   unsafe.Pointer
+//   yPlane+8(FP)   unsafe.Pointer
+//   coPlane+16(FP) unsafe.Pointer
+//   cgPlane+24(FP) unsafe.Pointer
+//   count+32(FP)   int
+//   shift+40(FP)   int
+
+#include "textflag.h"
+
+// func ycoCgToBGRANEON(pixels, yPlane, coPlane, cgPlane unsafe.Pointer, count, shift int)
+TEXT ·ycoCgToBGRANEON(SB),NOSPLIT,$0-48
+	MOVD pixels+0(FP),   R0   // dst
+	MOVD yPlane+8(FP),   R1   // Y plane
+	MOVD coPlane+16(FP), R2   // Co plane
+	MOVD cgPlane+24(FP), R3   // Cg plane
+	MOVD count+32(FP),   R4   // pixel count
+	MOVD shift+40(FP),   R5   // shift amount
+
+	CBZ  R4, done
+
+	MOVD $0,   R12   // const 0
+	MOVD $255, R13   // const 255
+
+loop:
+	MOVBU (R1), R6   // y  = Y[i]
+	MOVBU (R2), R7   // co = Co[i]
+	MOVBU (R3), R8   // cg = Cg[i]
+	ADD   $1, R1
+	ADD   $1, R2
+	ADD   $1, R3
+
+	// coVal = int8(co << shift): shift left, then sign-extend low byte.
+	LSL  R5, R7, R7     // R7 = co << shift  (low 8 bits hold result)
+	SXTB R7, R7         // R7 = int64(int8(R7))
+
+	// cgVal = int8(cg << shift)
+	LSL  R5, R8, R8
+	SXTB R8, R8
+
+	// B = clamp(y - co - cg)
+	SUB  R7, R6, R9     // R9 = y - co
+	SUB  R8, R9, R9     // R9 = y - co - cg
+	CMP  R12, R9
+	CSEL LT, R12, R9, R9
+	CMP  R13, R9
+	CSEL GT, R13, R9, R9
+
+	// G = clamp(y + cg)
+	ADD  R8, R6, R10    // R10 = y + cg
+	CMP  R12, R10
+	CSEL LT, R12, R10, R10
+	CMP  R13, R10
+	CSEL GT, R13, R10, R10
+
+	// R = clamp(y + co - cg)
+	ADD  R7, R6, R11    // R11 = y + co
+	SUB  R8, R11, R11   // R11 = y + co - cg
+	CMP  R12, R11
+	CSEL LT, R12, R11, R11
+	CMP  R13, R11
+	CSEL GT, R13, R11, R11
+
+	// Store BGRA pixel.
+	MOVBU R9, 0(R0)
+	MOVBU R10, 1(R0)
+	MOVBU R11, 2(R0)
+	MOVBU R13, 3(R0)    // alpha = 255
+	ADD  $4, R0
+
+	SUBS $1, R4, R4
+	BNE  loop
+
+done:
+	RET