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authorXavier ASUS <xavi92psx@gmail.com>2019-10-18 00:31:54 +0200
committerXavier ASUS <xavi92psx@gmail.com>2019-10-18 00:31:54 +0200
commit268a53de823a6750d6256ee1fb1e7707b4b45740 (patch)
tree42c1799a9a82b2f7d9790ee9fe181d72a7274751 /device/lib/tlcs90/divsigned.s
downloadsdcc-gas-268a53de823a6750d6256ee1fb1e7707b4b45740.tar.gz
sdcc-3.9.0 fork implementing GNU assembler syntax
This fork aims to provide better support for stm8-binutils
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+;--------------------------------------------------------------------------
+; divsigned.s
+;
+; Copyright (C) 2000-2010, Michael Hope, Philipp Klaus Krause
+;
+; This library 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 2, or (at your option) any
+; later version.
+;
+; This library 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.
+;
+; You should have received a copy of the GNU General Public License
+; along with this library; see the file COPYING. If not, write to the
+; Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
+; MA 02110-1301, USA.
+;
+; As a special exception, if you link this library with other files,
+; some of which are compiled with SDCC, to produce an executable,
+; this library does not by itself cause the resulting executable to
+; be covered by the GNU General Public License. This exception does
+; not however invalidate any other reasons why the executable file
+; might be covered by the GNU General Public License.
+;--------------------------------------------------------------------------
+
+.area _CODE
+
+.globl __divsint
+.globl __divschar
+
+__divsint:
+ ld hl, 2 (sp)
+ ld de, 4 (sp)
+
+ jp __div16
+
+__divschar:
+ ld hl, #2+1
+ add hl, sp
+
+ ld e, (hl)
+ dec hl
+ ld l, (hl)
+
+__div8::
+ ld a, l ; Sign extend
+ rlca
+ sbc a, a
+ ld h, a
+__div_signexte::
+ ld a, e ; Sign extend
+ rlca
+ sbc a, a
+ ld d, a
+ ; Fall through to __div16
+
+ ;; signed 16-bit division
+ ;;
+ ;; Entry conditions
+ ;; HL = dividend
+ ;; DE = divisor
+ ;;
+ ;; Exit conditions
+ ;; HL = quotient
+ ;; DE = remainder
+ ;;
+ ;; Register used: AF,B,DE,HL
+__div16::
+ ;; Determine sign of quotient by xor-ing high bytes of dividend
+ ;; and divisor. Quotient is positive if signs are the same, negative
+ ;; if signs are different
+ ;; Remainder has same sign as dividend
+ ld a, h ; Get high byte of dividend
+ xor a, d ; Xor with high byte of divisor
+ rla ; Sign of quotient goes into the carry
+ ld a, h ; Get high byte of dividend
+ push af ; Save sign of both quotient and reminder
+
+ ; Take absolute value of dividend
+ rla
+ jr NC, .chkde ; Jump if dividend is positive
+ sub a, a ; Substract dividend from 0
+ sub a, l
+ ld l, a
+ sbc a, a ; Propagate borrow (A=0xFF if borrow)
+ sub a, h
+ ld h, a
+
+ ; Take absolute value of divisor
+.chkde:
+ bit 7, d
+ jr Z, .dodiv ; Jump if divisor is positive
+ sub a, a ; Subtract divisor from 0
+ sub a, e
+ ld e, a
+ sbc a, a ; Propagate borrow (A=0xFF if borrow)
+ sub a, d
+ ld d, a
+
+ ; Divide absolute values
+.dodiv:
+ call __divu16
+
+.fix_quotient:
+ ; Negate quotient if it is negative
+ pop af ; recover sign of quotient
+ ret NC ; Jump if quotient is positive
+ ld b, a
+ sub a, a ; Subtract quotient from 0
+ sub a, l
+ ld l, a
+ sbc a, a ; Propagate borrow (A=0xFF if borrow)
+ sub a, h
+ ld h, a
+ ld a, b
+ ret
+
+__get_remainder::
+ ; Negate remainder if it is negative and move it into hl
+ rla
+ ex de, hl
+ ret NC ; Return if remainder is positive
+ sub a, a ; Subtract remainder from 0
+ sub a, l
+ ld l, a
+ sbc a, a ; Propagate remainder (A=0xFF if borrow)
+ sub a, h
+ ld h, a
+ ret
+