diff options
Diffstat (limited to 'gcc-4.4.3/gcc/config/picochip/libgccExtras/divmod15.asm')
| -rw-r--r-- | gcc-4.4.3/gcc/config/picochip/libgccExtras/divmod15.asm | 263 |
1 files changed, 263 insertions, 0 deletions
diff --git a/gcc-4.4.3/gcc/config/picochip/libgccExtras/divmod15.asm b/gcc-4.4.3/gcc/config/picochip/libgccExtras/divmod15.asm new file mode 100644 index 000000000..777adf279 --- /dev/null +++ b/gcc-4.4.3/gcc/config/picochip/libgccExtras/divmod15.asm @@ -0,0 +1,263 @@ +// picoChip ASM file +// +// Support for 16-bit unsigned division/modulus. +// +// Copyright (C) 2003, 2004, 2005, 2008, 2009 Free Software Foundation, Inc. +// Contributed by picoChip Designs Ltd. +// Maintained by Daniel Towner (daniel.towner@picochip.com) +// +// This file is free software; you can redistribute it and/or modify it +// under the terms of the GNU General Public License as published by the +// Free Software Foundation; either version 3, or (at your option) any +// later version. +// +// This file is distributed in the hope that it will be useful, but +// WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +// General Public License for more details. +// +// Under Section 7 of GPL version 3, you are granted additional +// permissions described in the GCC Runtime Library Exception, version +// 3.1, as published by the Free Software Foundation. +// +// You should have received a copy of the GNU General Public License and +// a copy of the GCC Runtime Library Exception along with this program; +// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see +// <http://www.gnu.org/licenses/>. + +.section .text + +.global __divmod15 +__divmod15: +_picoMark_FUNCTION_BEGIN= + +// picoChip Function Prologue : &__divmod15 = 0 bytes + +__divmod15: + + // The picoChip instruction set has a divstep instruction which + // is used to perform one iteration of a binary division algorithm. + // The instruction allows 16-bit signed division to be implemented. + // It does not directly allow 16-bit unsigned division to be + // implemented. Thus, this function pulls out the common division + // iteration for 15-bits unsigned, and then special wrappers + // provide the logic to change this into a 16-bit signed or + // unsigned division, as appropriate. This allows the two + // versions of division to share a common implementation, reducing + // code size when the two are used together. It also reduces + // the maintenance overhead. + + // Input: + // r0 - dividend + // r1 - divisor + // Output: + // r0 - quotient + // r1 - remainder + // R5 is unused + + // Check for special cases. The emphasis is on detecting these as + // quickly as possible, so that the main division can be started. If + // the user requests division by one, division by self, and so on + // then they will just have to accept that this won't be particularly + // quick (relatively), whereas a real division (e.g., dividing a + // large value by a small value) will run as fast as possible + // (i.e., special case detection should not slow down the common case) + // + // Special cases to consider: + // + // Division by zero. + // Division of zero. + // Inputs are equal + // Divisor is bigger than dividend + // Division by power of two (can be shifted instead). + // Division by 1 (special case of power of two division) + // + // Division/modulus by zero is undefined (ISO C:6.5.5), so + // don't bother handling this special case. + // + // The special cases of division by a power of 2 are ignored, since + // they cause the general case to slow down. Omitting these + // special cases also reduces code size considerably. + + // Handle divisor >= dividend separately. Note that this also handles + // the case where the dividend is zero. Note that the flags must be + // preserved, since they are also used at the branch destination. + sub.0 r1,r0,r15 + sbc r0,r2 \ bge divisorGeDividend +=-> sbc r1,r4 + + // Compute the shift count. The amount by which the divisor + // must be shifted left to be aligned with the dividend. + sub.0 r4,r2,r3 + + // Align the divisor to the dividend. Execute a divstep (since at + // least one will always be executed). Skip the remaining loop + // if the shift count is zero. + lsl.0 r1,r3,r1 \ beq skipLoop +=-> divstep r0,r1 \ add.1 r3,1,r2 + + // Execute the divstep loop until temp is 0. This assumes that the + // loop count is at least one. + sub.0 r3,1,r4 +divLoop: + divstep r0,r1 \ bne divLoop +=-> sub.0 r4,1,r4 + +skipLoop: + + // The top bits of the result are the remainder. The bottom + // bits are the quotient. + lsr.0 r0,r2,r1 \ sub.1 16,r2,r4 + jr (lr ) \ lsl.0 r0,r4,r0 +=-> lsr.0 r0,r4,r0 + +// Special case. + +divisorGeDividend: + // The divisor is greater than or equal to the dividend. The flags + // indicate which of these alternatives it is. The COPYNE can be used + // to set the result appropriately, without introducing any more + // branches. + copy.0 r0,r1 \ copy.1 0,r0 + jr (lr) \ copyeq r0,r1 +=-> copyeq 1,r0 + +_picoMark_FUNCTION_END= +// picoChip Function Epilogue : __divmod15 + + +//============================================================================ +// All DWARF information between this marker, and the END OF DWARF +// marker should be included in the source file. Search for +// FUNCTION_STACK_SIZE_GOES_HERE and FUNCTION NAME GOES HERE, and +// provide the relevent information. Add markers called +// _picoMark_FUNCTION_BEGIN and _picoMark_FUNCTION_END around the +// function in question. +//============================================================================ + +//============================================================================ +// Frame information. +//============================================================================ + +.section .debug_frame +_picoMark_DebugFrame= + +// Common CIE header. +.unalignedInitLong _picoMark_CieEnd-_picoMark_CieBegin +_picoMark_CieBegin= +.unalignedInitLong 0xffffffff +.initByte 0x1 // CIE Version +.ascii 16#0# // CIE Augmentation +.uleb128 0x1 // CIE Code Alignment Factor +.sleb128 2 // CIE Data Alignment Factor +.initByte 0xc // CIE RA Column +.initByte 0xc // DW_CFA_def_cfa +.uleb128 0xd +.uleb128 0x0 +.align 2 +_picoMark_CieEnd= + +// FDE +_picoMark_LSFDE0I900821033007563= +.unalignedInitLong _picoMark_FdeEnd-_picoMark_FdeBegin +_picoMark_FdeBegin= +.unalignedInitLong _picoMark_DebugFrame // FDE CIE offset +.unalignedInitWord _picoMark_FUNCTION_BEGIN // FDE initial location +.unalignedInitWord _picoMark_FUNCTION_END-_picoMark_FUNCTION_BEGIN +.initByte 0xe // DW_CFA_def_cfa_offset +.uleb128 0x0 // <-- FUNCTION_STACK_SIZE_GOES_HERE +.initByte 0x4 // DW_CFA_advance_loc4 +.unalignedInitLong _picoMark_FUNCTION_END-_picoMark_FUNCTION_BEGIN +.initByte 0xe // DW_CFA_def_cfa_offset +.uleb128 0x0 +.align 2 +_picoMark_FdeEnd= + +//============================================================================ +// Abbrevation information. +//============================================================================ + +.section .debug_abbrev +_picoMark_ABBREVIATIONS= + +.section .debug_abbrev + .uleb128 0x1 // (abbrev code) + .uleb128 0x11 // (TAG: DW_TAG_compile_unit) + .initByte 0x1 // DW_children_yes + .uleb128 0x10 // (DW_AT_stmt_list) + .uleb128 0x6 // (DW_FORM_data4) + .uleb128 0x12 // (DW_AT_high_pc) + .uleb128 0x1 // (DW_FORM_addr) + .uleb128 0x11 // (DW_AT_low_pc) + .uleb128 0x1 // (DW_FORM_addr) + .uleb128 0x25 // (DW_AT_producer) + .uleb128 0x8 // (DW_FORM_string) + .uleb128 0x13 // (DW_AT_language) + .uleb128 0x5 // (DW_FORM_data2) + .uleb128 0x3 // (DW_AT_name) + .uleb128 0x8 // (DW_FORM_string) +.initByte 0x0 +.initByte 0x0 + + .uleb128 0x2 ;# (abbrev code) + .uleb128 0x2e ;# (TAG: DW_TAG_subprogram) +.initByte 0x0 ;# DW_children_no + .uleb128 0x3 ;# (DW_AT_name) + .uleb128 0x8 ;# (DW_FORM_string) + .uleb128 0x11 ;# (DW_AT_low_pc) + .uleb128 0x1 ;# (DW_FORM_addr) + .uleb128 0x12 ;# (DW_AT_high_pc) + .uleb128 0x1 ;# (DW_FORM_addr) +.initByte 0x0 +.initByte 0x0 + +.initByte 0x0 + +//============================================================================ +// Line information. DwarfLib requires this to be present, but it can +// be empty. +//============================================================================ + +.section .debug_line +_picoMark_LINES= + +//============================================================================ +// Debug Information +//============================================================================ +.section .debug_info + +//Fixed header. +.unalignedInitLong _picoMark_DEBUG_INFO_END-_picoMark_DEBUG_INFO_BEGIN +_picoMark_DEBUG_INFO_BEGIN= +.unalignedInitWord 0x2 +.unalignedInitLong _picoMark_ABBREVIATIONS +.initByte 0x2 + +// Compile unit information. +.uleb128 0x1 // (DIE 0xb) DW_TAG_compile_unit) +.unalignedInitLong _picoMark_LINES +.unalignedInitWord _picoMark_FUNCTION_END +.unalignedInitWord _picoMark_FUNCTION_BEGIN +// Producer is `picoChip' +.ascii 16#70# 16#69# 16#63# 16#6f# 16#43# 16#68# 16#69# 16#70# 16#00# +.unalignedInitWord 0xcafe // ASM language +.ascii 16#0# // Name. DwarfLib expects this to be present. + +.uleb128 0x2 ;# (DIE DW_TAG_subprogram) + +// FUNCTION NAME GOES HERE. Use `echo name | od -t x1' to get the hex. Each hex +// digit is specified using the format 16#XX# +.ascii 16#5f# 16#64# 16#69# 16#76# 16#6d# 16#6f# 16#64# 16#31# 16#35# 16#0# // Function name `_divmod15' +.unalignedInitWord _picoMark_FUNCTION_BEGIN // DW_AT_low_pc +.unalignedInitWord _picoMark_FUNCTION_END // DW_AT_high_pc + +.initByte 0x0 // end of compile unit children. + +_picoMark_DEBUG_INFO_END= + +//============================================================================ +// END OF DWARF +//============================================================================ + +.section .endFile +// End of picoChip ASM file |