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Diffstat (limited to 'zap/source/arm/sys/syscall.s')
| -rw-r--r-- | zap/source/arm/sys/syscall.s | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/zap/source/arm/sys/syscall.s b/zap/source/arm/sys/syscall.s new file mode 100644 index 0000000..c4f8d40 --- /dev/null +++ b/zap/source/arm/sys/syscall.s @@ -0,0 +1,32 @@ +@ Copyright 2022-2023 Gabriel Jensen. +@ This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. +@ If a copy of the MPL was not distributed with this file, You can obtain one at <https://mozilla.org/MPL/2.0>. + +.syntax unified + +.arm + +.globl zap_syscall + +zap_syscall: + @ System calls on ARM EABI use the following registers: + @ r0 : System call identifier + @ r1 : First parameter + @ r2 : Second parameter + @ r3 : Third parameter + @ r4 : Fourth parameter + @ r5 : Fifth parameter + @ r6 : Sixth parameter + @ r0 : Return value + push {r4-r5,r7,lr} @ Remember that the parameters are now further up the stack. + mov r7,r0 @ Move the identifier. + mov r0,r1 @ Place parameters. + mov r1,r2 + mov r2,r3 + ldr r3,[sp,0x10] @ Get the remaining parameters from the stack. + ldr r4,[sp,0x14] + ldr r5,[sp,0x18] + svc 0x0 @ Divinity + pop {r4-r5,r7} @ Restore the registers. + pop {r0} + bx r0 |