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- // SPDX-License-Identifier: Apache-2.0
- // SPDX-FileCopyrightText: 2026 The Ebitengine Authors
- //go:build linux
- #include "textflag.h"
- #include "go_asm.h"
- #include "funcdata.h"
- #define STACK_SIZE 128
- #define PTR_ADDRESS (STACK_SIZE - 4)
- // syscall15X calls a function in libc on behalf of the syscall package.
- // syscall15X takes a pointer to a struct like:
- // struct {
- // fn uintptr
- // a1 uintptr
- // ...
- // a32 uintptr
- // f1 uintptr
- // ...
- // f16 uintptr
- // arm64_r8 uintptr
- // }
- // syscall15X must be called on the g0 stack with the
- // C calling convention (use libcCall).
- GLOBL ·syscall15XABI0(SB), NOPTR|RODATA, $4
- DATA ·syscall15XABI0(SB)/4, $syscall15X(SB)
- TEXT syscall15X(SB), NOSPLIT|NOFRAME, $0-0
- // Called via C calling convention: R0 = pointer to syscall15Args
- // NOT via Go calling convention
- // Save link register and callee-saved registers first
- MOVW.W R14, -4(R13) // save LR (decrement and store)
- MOVM.DB.W [R4, R5, R6, R7, R8, R9, R11], (R13) // save callee-saved regs
- MOVW R0, R8
- SUB $STACK_SIZE, R13
- MOVW R8, PTR_ADDRESS(R13)
- // Load function pointer first (before anything can corrupt R8)
- MOVW syscall15Args_fn(R8), R5
- MOVW R5, (PTR_ADDRESS-4)(R13) // save fn at offset 56
- // Load floating point arguments
- // Each float64 spans 2 uintptr slots (8 bytes) on ARM32, so we skip by 2
- MOVD syscall15Args_f1(R8), F0 // f1+f2 -> D0
- MOVD syscall15Args_f3(R8), F1 // f3+f4 -> D1
- MOVD syscall15Args_f5(R8), F2 // f5+f6 -> D2
- MOVD syscall15Args_f7(R8), F3 // f7+f8 -> D3
- MOVD syscall15Args_f9(R8), F4 // f9+f10 -> D4
- MOVD syscall15Args_f11(R8), F5 // f11+f12 -> D5
- MOVD syscall15Args_f13(R8), F6 // f13+f14 -> D6
- MOVD syscall15Args_f15(R8), F7 // f15+f16 -> D7
- // Load integer arguments into registers (R0-R3 for ARM EABI)
- MOVW syscall15Args_a1(R8), R0 // a1
- MOVW syscall15Args_a2(R8), R1 // a2
- MOVW syscall15Args_a3(R8), R2 // a3
- MOVW syscall15Args_a4(R8), R3 // a4
- // push a5-a32 onto stack
- MOVW syscall15Args_a5(R8), R4
- MOVW R4, 0(R13)
- MOVW syscall15Args_a6(R8), R4
- MOVW R4, 4(R13)
- MOVW syscall15Args_a7(R8), R4
- MOVW R4, 8(R13)
- MOVW syscall15Args_a8(R8), R4
- MOVW R4, 12(R13)
- MOVW syscall15Args_a9(R8), R4
- MOVW R4, 16(R13)
- MOVW syscall15Args_a10(R8), R4
- MOVW R4, 20(R13)
- MOVW syscall15Args_a11(R8), R4
- MOVW R4, 24(R13)
- MOVW syscall15Args_a12(R8), R4
- MOVW R4, 28(R13)
- MOVW syscall15Args_a13(R8), R4
- MOVW R4, 32(R13)
- MOVW syscall15Args_a14(R8), R4
- MOVW R4, 36(R13)
- MOVW syscall15Args_a15(R8), R4
- MOVW R4, 40(R13)
- MOVW syscall15Args_a16(R8), R4
- MOVW R4, 44(R13)
- MOVW syscall15Args_a17(R8), R4
- MOVW R4, 48(R13)
- MOVW syscall15Args_a18(R8), R4
- MOVW R4, 52(R13)
- MOVW syscall15Args_a19(R8), R4
- MOVW R4, 56(R13)
- MOVW syscall15Args_a20(R8), R4
- MOVW R4, 60(R13)
- MOVW syscall15Args_a21(R8), R4
- MOVW R4, 64(R13)
- MOVW syscall15Args_a22(R8), R4
- MOVW R4, 68(R13)
- MOVW syscall15Args_a23(R8), R4
- MOVW R4, 72(R13)
- MOVW syscall15Args_a24(R8), R4
- MOVW R4, 76(R13)
- MOVW syscall15Args_a25(R8), R4
- MOVW R4, 80(R13)
- MOVW syscall15Args_a26(R8), R4
- MOVW R4, 84(R13)
- MOVW syscall15Args_a27(R8), R4
- MOVW R4, 88(R13)
- MOVW syscall15Args_a28(R8), R4
- MOVW R4, 92(R13)
- MOVW syscall15Args_a29(R8), R4
- MOVW R4, 96(R13)
- MOVW syscall15Args_a30(R8), R4
- MOVW R4, 100(R13)
- MOVW syscall15Args_a31(R8), R4
- MOVW R4, 104(R13)
- MOVW syscall15Args_a32(R8), R4
- MOVW R4, 108(R13)
- // Load saved function pointer and call
- MOVW (PTR_ADDRESS-4)(R13), R4
- // Use BLX for Thumb interworking - Go assembler doesn't support BLX Rn
- // BLX R4 = 0xE12FFF34 (ARM encoding, always condition)
- WORD $0xE12FFF34 // blx r4
- // pop structure pointer
- MOVW PTR_ADDRESS(R13), R8
- ADD $STACK_SIZE, R13
- // save R0, R1
- MOVW R0, syscall15Args_a1(R8)
- MOVW R1, syscall15Args_a2(R8)
- // save f0-f3 (each float64 spans 2 uintptr slots on ARM32)
- MOVD F0, syscall15Args_f1(R8)
- MOVD F1, syscall15Args_f3(R8)
- MOVD F2, syscall15Args_f5(R8)
- MOVD F3, syscall15Args_f7(R8)
- // Restore callee-saved registers and return
- MOVM.IA.W (R13), [R4, R5, R6, R7, R8, R9, R11]
- MOVW.P 4(R13), R15 // pop LR into PC (return)
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