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Diffstat (limited to 'c/src/lib/libcpu/sparc/reg_win/window.S')
| -rw-r--r-- | c/src/lib/libcpu/sparc/reg_win/window.S | 257 |
1 files changed, 257 insertions, 0 deletions
diff --git a/c/src/lib/libcpu/sparc/reg_win/window.S b/c/src/lib/libcpu/sparc/reg_win/window.S new file mode 100644 index 0000000000..c21e73ebb4 --- /dev/null +++ b/c/src/lib/libcpu/sparc/reg_win/window.S @@ -0,0 +1,257 @@ +/* + * window.s + * + * This file contains the register window management routines for the + * SPARC architecture. Trap handlers for the following capabilities + * are included in this file: + * + * + Window Overflow + * + Window Underflow + * + Flushing All Windows + * + * COPYRIGHT: + * + * This file includes the window overflow and underflow handlers from + * the file srt0.s provided with the binary distribution of the SPARC + * Instruction Simulator (SIS) found at + * ftp://ftp.estec.esa.nl/pub/ws/wsd/erc32. + * + * COPYRIGHT (c) 1995. European Space Agency. + * + * This terms of the RTEMS license apply to this file. + * + * $Id$ + */ + +#include <asm.h> + + .seg "text" + /* + * Window overflow trap handler. + * + * On entry: + * + * l0 = psr (from trap table) + * l1 = pc + * l2 = npc + */ + + PUBLIC(window_overflow_trap_handler) + +SYM(window_overflow_trap_handler): + + /* + * Calculate new WIM by "rotating" the valid bits in the WIM right + * by one position. The following shows how the bits move for a SPARC + * cpu implementation where SPARC_NUMBER_OF_REGISTER_WINDOWS is 8. + * + * OLD WIM = 76543210 + * NEW WIM = 07654321 + * + * NOTE: New WIM must be stored in a global register since the + * "save" instruction just prior to the load of the wim + * register will result in the local register set changing. + */ + + mov %wim, %l3 ! l3 = WIM + mov %g1, %l7 ! save g1 + srl %l3, 1, %g1 ! g1 = WIM >> 1 + sll %l3, SPARC_NUMBER_OF_REGISTER_WINDOWS-1 , %l4 + ! l4 = WIM << (Number Windows - 1) + or %l4, %g1, %g1 ! g1 = (WIM >> 1) | + ! (WIM << (Number Windows - 1)) + + save ! Get into window to be saved. + mov %g1, %wim ! load new WIM + nop; nop; nop ! 3 slot delay + std %l0, [%sp + 0x00] ! save local register set + std %l2, [%sp + 0x08] + std %l4, [%sp + 0x10] + std %l6, [%sp + 0x18] + std %i0, [%sp + 0x20] ! save input register set + std %i2, [%sp + 0x28] + std %i4, [%sp + 0x30] + std %i6, [%sp + 0x38] + restore ! Go back to trap window. + mov %l7, %g1 ! restore g1 + jmp %l1 ! Re-execute save. + rett %l2 + + /* + * Window underflow trap handler. + * + * On entry: + * + * l0 = psr (from trap table) + * l1 = pc + * l2 = npc + */ + + PUBLIC(window_underflow_trap_handler) + +SYM(window_underflow_trap_handler): + + /* + * Calculate new WIM by "rotating" the valid bits in the WIM left + * by one position. The following shows how the bits move for a SPARC + * cpu implementation where SPARC_NUMBER_OF_REGISTER_WINDOWS is 8. + * + * OLD WIM = 76543210 + * NEW WIM = 07654321 + * + * NOTE: New WIM must be stored in a global register since the + * "save" instruction just prior to the load of the wim + * register will result in the local register set changing. + */ + + mov %wim, %l3 ! Calculate new WIM + sll %l3, 1, %l4 ! l4 = WIM << 1 + srl %l3, SPARC_NUMBER_OF_REGISTER_WINDOWS-1, %l5 + ! l5 = WIM >> (Number Windows-1) + or %l5, %l4, %l5 ! l5 = (WIM << 1) | + ! (WIM >> (Number Windows-1)) + mov %l5, %wim ! load the new WIM + nop; nop; nop + restore ! Two restores to get into the + restore ! window to restore + ldd [%sp + 0x00], %l0 ! First the local register set + ldd [%sp + 0x08], %l2 + ldd [%sp + 0x10], %l4 + ldd [%sp + 0x18], %l6 + ldd [%sp + 0x20], %i0 ! Then the input registers + ldd [%sp + 0x28], %i2 + ldd [%sp + 0x30], %i4 + ldd [%sp + 0x38], %i6 + save ! Get back to the trap window. + save + jmp %l1 ! Re-execute restore. + rett %l2 + + /* + * Flush All Windows trap handler. + * + * Flush all windows with valid contents except the current one + * and the one we will be returning to. + * + * In examining the set register windows, one may logically divide + * the windows into sets (some of which may be empty) based on their + * current status: + * + * + current (i.e. in use), + * + used (i.e. a restore would not trap) + * + invalid (i.e. 1 in corresponding bit in WIM) + * + unused + * + * Either the used or unused set of windows may be empty. + * + * NOTE: We assume only one bit is set in the WIM at a time. + * + * Given a CWP of 5 and a WIM of 0x1, the registers are divided + * into sets as follows: + * + * + 0 - invalid + * + 1-4 - unused + * + 5 - current + * + 6-7 - used + * + * In this case, we only would save the used windows which we + * will not be returning to -- 6. + * + * Register Usage while saving the windows: + * g1 = current PSR + * g2 = current wim + * g3 = CWP + * g4 = wim scratch + * g5 = scratch + * + * On entry: + * + * l0 = psr (from trap table) + * l1 = pc + * l2 = npc + */ + + PUBLIC(window_flush_trap_handler) + +SYM(window_flush_trap_handler): + /* + * Save the global registers we will be using + */ + + mov %g1, %l3 + mov %g2, %l4 + mov %g3, %l5 + mov %g4, %l6 + mov %g5, %l7 + + mov %l0, %g1 ! g1 = psr + mov %wim, %g2 ! g2 = wim + and %l0, SPARC_PSR_CWP_MASK, %g3 ! g3 = CWP + + add %g3, 1, %g5 ! g5 = CWP + 1 + and %g5, SPARC_NUMBER_OF_REGISTER_WINDOWS - 1, %g5 + + mov 1, %g4 + sll %g4, %g5, %g4 ! g4 = WIM mask for CWP+1 invalid + + restore ! go back one register window + +save_frame_loop: + sll %g4, 1, %g5 ! rotate the "wim" left 1 + srl %g4, SPARC_NUMBER_OF_REGISTER_WINDOWS - 1, %g4 + or %g4, %g5, %g4 ! g4 = wim if we do one restore + + /* + * If a restore would not underflow, then continue. + */ + + andcc %g4, %g2, %g0 ! Any windows to flush? + bnz done_flushing ! No, then continue + nop + + restore ! back one window + + /* + * Now save the window just as if we overflowed to it. + */ + + std %l0, [%sp + CPU_STACK_FRAME_L0_OFFSET] + std %l2, [%sp + CPU_STACK_FRAME_L2_OFFSET] + std %l4, [%sp + CPU_STACK_FRAME_L4_OFFSET] + std %l6, [%sp + CPU_STACK_FRAME_L6_OFFSET] + + std %i0, [%sp + CPU_STACK_FRAME_I0_OFFSET] + std %i2, [%sp + CPU_STACK_FRAME_I2_OFFSET] + std %i4, [%sp + CPU_STACK_FRAME_I4_OFFSET] + std %i6, [%sp + CPU_STACK_FRAME_I6_FP_OFFSET] + + ba save_frame_loop + nop + +done_flushing: + + add %g3, 2, %g3 ! calculate desired WIM + and %g3, SPARC_NUMBER_OF_REGISTER_WINDOWS - 1, %g3 + mov 1, %g4 + sll %g4, %g3, %g4 ! g4 = new WIM + mov %g4, %wim + + mov %g1, %psr ! restore PSR + nop + nop + nop + + /* + * Restore the global registers we used + */ + + mov %l3, %g1 + mov %l4, %g2 + mov %l5, %g3 + mov %l6, %g4 + mov %l7, %g5 + + jmpl %l2, %g0 + rett %l2 + 4 + +/* end of file */ |