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Diffstat (limited to 'c/src/exec/score/cpu/m68k/cpu_asm.s')
| -rw-r--r-- | c/src/exec/score/cpu/m68k/cpu_asm.s | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/c/src/exec/score/cpu/m68k/cpu_asm.s b/c/src/exec/score/cpu/m68k/cpu_asm.s new file mode 100644 index 0000000000..d8615627a0 --- /dev/null +++ b/c/src/exec/score/cpu/m68k/cpu_asm.s @@ -0,0 +1,202 @@ +/* cpu_asm.s + * + * This file contains all assembly code for the MC68020 implementation + * of RTEMS. + * + * COPYRIGHT (c) 1989, 1990, 1991, 1992, 1993, 1994. + * On-Line Applications Research Corporation (OAR). + * All rights assigned to U.S. Government, 1994. + * + * This material may be reproduced by or for the U.S. Government pursuant + * to the copyright license under the clause at DFARS 252.227-7013. This + * notice must appear in all copies of this file and its derivatives. + * + * $Id$ + */ + + +#include <asm.h> + + .text + +/* void _CPU_Context_switch( run_context, heir_context ) + * + * This routine performs a normal non-FP context. + */ + + .align 4 + .global SYM (_CPU_Context_switch) + +.set RUNCONTEXT_ARG, 4 | save context argument +.set HEIRCONTEXT_ARG, 8 | restore context argument + +SYM (_CPU_Context_switch): + moval a7@(RUNCONTEXT_ARG),a0| a0 = running thread context + movw sr,d1 | d1 = status register + movml d1-d7/a2-a7,a0@ | save context + + moval a7@(HEIRCONTEXT_ARG),a0| a0 = heir thread context +restore: movml a0@,d1-d7/a2-a7 | restore context + movw d1,sr | restore status register + rts + +/*PAGE + * void __CPU_Context_save_fp_context( &fp_context_ptr ) + * void __CPU_Context_restore_fp_context( &fp_context_ptr ) + * + * These routines are used to context switch a MC68881 or MC68882. + * + * NOTE: Context save and restore code is based upon the code shown + * on page 6-38 of the MC68881/68882 Users Manual (rev 1). + * + * CPU_FP_CONTEXT_SIZE is higher than expected to account for the + * -1 pushed at end of this sequence. + */ + +.set FPCONTEXT_ARG, 4 | save FP context argument + + .align 4 + .global SYM (_CPU_Context_save_fp) +SYM (_CPU_Context_save_fp): +#if ( M68K_HAS_FPU == 1 ) + moval a7@(FPCONTEXT_ARG),a1 | a1 = &ptr to context area + moval a1@,a0 | a0 = Save context area + fsave a0@- | save 68881/68882 state frame + tstb a0@ | check for a null frame + beq nosv | Yes, skip save of user model + fmovem fp0-fp7,a0@- | save data registers (fp0-fp7) + fmovem fpc/fps/fpi,a0@- | and save control registers + movl #-1,a0@- | place not-null flag on stack +nosv: movl a0,a1@ | save pointer to saved context +#endif + rts + + .align 4 + .global SYM (_CPU_Context_restore_fp) +SYM (_CPU_Context_restore_fp): +#if ( M68K_HAS_FPU == 1 ) + moval a7@(FPCONTEXT_ARG),a1 | a1 = &ptr to context area + moval a1@,a0 | a0 = address of saved context + tstb a0@ | Null context frame? + beq norst | Yes, skip fp restore + addql #4,a0 | throwaway non-null flag + fmovem a0@+,fpc/fps/fpi | restore control registers + fmovem a0@+,fp0-fp7 | restore data regs (fp0-fp7) +norst: frestore a0@+ | restore the fp state frame + movl a0,a1@ | save pointer to saved context +#endif + rts + +/*PAGE + * void _ISR_Handler() + * + * This routine provides the RTEMS interrupt management. + * + * NOTE: + * Upon entry, the master stack will contain an interrupt stack frame + * back to the interrupted thread and the interrupt stack will contain + * a throwaway interrupt stack frame. If dispatching is enabled, this + * is the outer most interrupt, and (a context switch is necessary or + * the current thread has signals), then set up the master stack to + * transfer control to the interrupt dispatcher. + */ + +.set SR_OFFSET, 0 | Status register offset +.set PC_OFFSET, 2 | Program Counter offset +.set FVO_OFFSET, 6 | Format/vector offset + +.set SAVED, 16 | space for saved registers + + .align 4 + .global SYM (_ISR_Handler) + +SYM (_ISR_Handler): + moveml d0-d1/a0-a1,a7@- | save d0-d1,a0-a1 + addql #1,SYM (_ISR_Nest_level) | one nest level deeper + addql #1,SYM (_Thread_Dispatch_disable_level) + | disable multitasking + movew a7@(SAVED+FVO_OFFSET),d0 | d0 = F/VO + andl #0x0fff,d0 | d0 = vector offset in vbr + +#if ( M68K_HAS_PREINDEXING == 1 ) + movel @( SYM (_ISR_Vector_table),d0:w:1),a0| fetch the ISR +#else + movel # SYM (_ISR_Vector_table),a0 | a0 = base of RTEMS table + addal d0,a0 | a0 = address of vector + movel @(a0),a0 | a0 = address of user routine +#warning "UNTESTED CODE!!!" +#endif + + lsrl #2,d0 | d0 = vector number + movel d0,a7@- | push vector number + jbsr a0@ | invoke the user ISR + addql #4,a7 | remove vector number + + subql #1,SYM (_ISR_Nest_level) | one less nest level + subql #1,SYM (_Thread_Dispatch_disable_level) + | unnest multitasking + bne exit | If dispatch disabled, exit + + movew #0xf000,d0 | isolate format nibble + andw a7@(SAVED+FVO_OFFSET),d0 | get F/VO + cmpiw #0x1000,d0 | is it a throwaway isf? + bne exit | NOT outer level, so branch + + tstl SYM (_Context_Switch_necessary) + | Is thread switch necessary? + bne bframe | Yes, invoke dispatcher + + tstl SYM (_ISR_Signals_to_thread_executing) + | signals sent to Run_thread + | while in interrupt handler? + beq exit | No, then exit + + +bframe: clrl SYM (_ISR_Signals_to_thread_executing) + | If sent, will be processed +#if ( M68K_HAS_SEPARATE_STACKS == 1 ) + movec msp,a0 | a0 = master stack pointer + movew #0,a0@- | push format word + movel # SYM (_ISR_Dispatch),a0@- | push return addr + movew a0@(6+SR_OFFSET),a0@- | push thread sr + movec a0,msp | set master stack pointer +#else +#warning "FIX ME ... HOW DO I DISPATCH FROM AN INTERRUPT?" +/* probably will simply need to push the _ISR_Dispatch frame */ +#endif + +exit: moveml a7@+,d0-d1/a0-a1 | restore d0-d1,a0-a1 + rte | return to thread + | OR _Isr_dispatch + +/*PAGE + * void _ISR_Dispatch() + * + * Entry point from the outermost interrupt service routine exit. + * The current stack is the supervisor mode stack if this processor + * has separate stacks. + * + * 1. save all registers not preserved across C calls. + * 2. invoke the _Thread_Dispatch routine to switch tasks + * or a signal to the currently executing task. + * 3. restore all registers not preserved across C calls. + * 4. return from interrupt + */ + + .global SYM (_ISR_Dispatch) +SYM (_ISR_Dispatch): + movml d0-d1/a0-a1,a7@- + jsr SYM (_Thread_Dispatch) + movml a7@+,d0-d1/a0-a1 + rte + + + + + + + + + + + |