zx128: Add syscall entry point

This needs some further thought. If we are going to support relocatable
binaries we will need some way to fix up the syscall entry point on them.

diff --git a/Kernel/platform-zx128/zx128.s b/Kernel/platform-zx128/zx128.s
index d7297c4..6ea88fe 100644 (file)
--- a/Kernel/platform-zx128/zx128.s
+++ b/Kernel/platform-zx128/zx128.s
@@ -10,6 +10,7 @@
         .globl _program_vectors
         .globl platform_interrupt_all
        .globl interrupt_handler
+       .globl unix_syscall_entry
 
         .globl map_kernel
         .globl map_process
@@ -159,9 +160,12 @@ setvectors:
        ld a, #0x18
        ld (0xffff), a          ;       JR (plus ROM at 0 gives JR $FFF4)
        ld a, #0xC3             ;       JP
-       ld (0xFFF4), a
+       ld (0xFFF4), a          ;       FFF4-6 are the interrupt vector
+       ld (0xFFF7), a          ;       FFF7-9 are syscall
        ld hl, #interrupt_handler
        ld (0xFFF5), hl         ;       to IRQ handler
+       ld hl, #unix_syscall_entry
+       ld (0xFFF8), hl         ;       system calls (can't use RST on this box)
        call map_restore
        ret